diff --git a/LOG b/LOG
index 366d9d29f0..6942081fb1 100644
--- a/LOG
+++ b/LOG
@@ -532,3 +532,8 @@
 - don't remove the pariah form in the cp0 pass
     cp0.ss,
     misc.ms
+- revert use of ephemerons in weak hashtables, add ephemeron
+  hashtables
+    newhash.ss, hashtable-types.ss, library.ss, primdata.ss,
+    fasl.ss, fasl.c, gc.c, globals.h,
+    hash.ms, objects.stex, release_notes.stex
\ No newline at end of file
diff --git a/c/fasl.c b/c/fasl.c
index 8bc65837a7..e24934d4d7 100644
--- a/c/fasl.c
+++ b/c/fasl.c
@@ -722,7 +722,7 @@ static void faslin(ptr tc, ptr *x, ptr t, ptr *pstrbuf, faslFile f) {
             return;
         }
         case fasl_type_eq_hashtable: {
-            ptr rtd, ht, v; IBOOL weakp; uptr veclen, i, n;
+            ptr rtd, ht, v; uptr subtype; uptr veclen, i, n;
             if ((rtd = S_G.eq_ht_rtd) == Sfalse) {
               S_G.eq_ht_rtd = rtd = SYMVAL(S_intern((const unsigned char *)"$eq-ht-rtd"));
               if (!Srecordp(rtd)) S_error_abort("$eq-ht-rtd has not been set");
@@ -731,7 +731,15 @@ static void faslin(ptr tc, ptr *x, ptr t, ptr *pstrbuf, faslFile f) {
             RECORDINSTTYPE(ht) = rtd;
             INITPTRFIELD(ht,eq_hashtable_type_disp) = S_G.eq_symbol;
             INITPTRFIELD(ht,eq_hashtable_mutablep_disp) = bytein(f) ? Strue : Sfalse;
-            INITPTRFIELD(ht,eq_hashtable_weakp_disp) = (weakp = bytein(f)) ? Strue : Sfalse;
+            switch ((subtype = bytein(f))) {
+            case eq_hashtable_subtype_normal:
+            case eq_hashtable_subtype_weak:
+            case eq_hashtable_subtype_ephemeron:
+              INITPTRFIELD(ht,eq_hashtable_subtype_disp) = FIX(subtype);
+              break;
+            default:
+              S_error2("", "invalid eq-hashtable subtype code", FIX(subtype), f->uf->path);
+            }
             INITPTRFIELD(ht,eq_hashtable_minlen_disp) = FIX(uptrin(f));
             veclen = uptrin(f);
             INITPTRFIELD(ht,eq_hashtable_vec_disp) = v = S_vector(veclen);
@@ -740,7 +748,18 @@ static void faslin(ptr tc, ptr *x, ptr t, ptr *pstrbuf, faslFile f) {
             for (i = 0; i < veclen ; i += 1) { INITVECTIT(v, i) = FIX(i); }
             while (n > 0) {
               ptr keyval;
-              keyval = weakp ? S_cons_in(space_weakpair, 0, FIX(0), FIX(0)) : Scons(FIX(0), FIX(0));
+              switch (subtype) {
+              case eq_hashtable_subtype_normal:
+                keyval = Scons(FIX(0), FIX(0));
+                break;
+              case eq_hashtable_subtype_weak:
+                keyval = S_cons_in(space_weakpair, 0, FIX(0), FIX(0));
+                break;
+              case eq_hashtable_subtype_ephemeron:
+              default:
+                keyval = S_cons_in(space_ephemeron, 0, FIX(0), FIX(0));
+                break;
+              }
               faslin(tc, &INITCAR(keyval), t, pstrbuf, f);
               faslin(tc, &INITCDR(keyval), t, pstrbuf, f);
               i = ((uptr)Scar(keyval) >> primary_type_bits) & (veclen - 1);
diff --git a/c/gc.c b/c/gc.c
index e67bf87ddc..329d576eba 100644
--- a/c/gc.c
+++ b/c/gc.c
@@ -1205,7 +1205,7 @@ void GCENTRY(ptr tc, IGEN mcg, IGEN tg) {
       for (b = TLCNEXT(tlc); !Sfixnump(b); b = TLCNEXT(b));
       old_idx = UNFIX(b);
 
-      if (key == Sbwp_object && PTRFIELD(ht,eq_hashtable_weakp_disp) != Sfalse) {
+      if (key == Sbwp_object && PTRFIELD(ht,eq_hashtable_subtype_disp) != FIX(eq_hashtable_subtype_normal)) {
        /* remove tlc */
         b = Svector_ref(vec, old_idx);
         if (b == tlc) {
diff --git a/csug/objects.stex b/csug/objects.stex
index d243e7107a..f92a428756 100644
--- a/csug/objects.stex
+++ b/csug/objects.stex
@@ -1847,9 +1847,13 @@ except the keys of the hashtable are held weakly, i.e., they are not
 protected from the garbage collector.
 Keys reclaimed by the garbage collector are removed from the table,
 and their associated values are dropped the next time the table
-is modified, if not sooner. A value in the hashtable can refer to a
-key in the hashtable without preventing the garbage collector from
-reclaiming the key (because keys are paired values using ephemeron pairs).
+is modified, if not sooner.
+
+Values in the hashtable are referenced normally as long as the key is
+not reclaimed, since keys are paired values using weak pairs. Consequently,
+if a value in the hashtable refers to its own key, then
+garbage collection is prevented from reclaiming the key. See
+\scheme{make-ephemeron-eq-hashtable} and \scheme{make-ephemeron-eqv-hashtable}.
 
 A copy of a weak eq or eqv hashtable created by \scheme{hashtable-copy} is
 also weak.
@@ -1864,6 +1868,32 @@ The effect of this can be observed via \scheme{hashtable-keys} and
 \endschemedisplay
 
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{make-ephemeron-eq-hashtable}{\categoryprocedure}{(make-ephemeron-eq-hashtable)}
+\formdef{make-ephemeron-eq-hashtable}{\categoryprocedure}{(make-ephemeron-eq-hashtable \var{size})}
+\formdef{make-ephemeron-eqv-hashtable}{\categoryprocedure}{(make-ephemeron-eqv-hashtable)}
+\formdef{make-ephemeron-eqv-hashtable}{\categoryprocedure}{(make-ephemeron-eqv-hashtable \var{size})}
+\returns a new ephemeron eq hashtable
+\listlibraries
+\endentryheader
+
+These procedures are like \scheme{make-weak-eq-hashtable} and
+\scheme{make-weak-eqv-hashtable}, but a value in the hashtable can refer to a
+key in the hashtable without preventing garbage collection from
+reclaiming the key, because keys are paired with values using ephemeron pairs.
+
+A copy of an ephemeron eq or eqv hashtable created by
+\scheme{hashtable-copy} is also an ephemeron table, and inaccesible
+key can be dropped from an immutable ephemeron hashtable in the same
+way as for an immutable weak hashtable.
+
+\schemedisplay
+(define ht1 (make-ephemeron-eq-hashtable))
+(define ht2 (make-ephemeron-eq-hashtable 32))
+\endschemedisplay
+
+
 %----------------------------------------------------------------------------
 \entryheader
 \formdef{hashtable-weak?}{\categoryprocedure}{(hashtable-weak? \var{obj})}
@@ -1878,6 +1908,20 @@ The effect of this can be observed via \scheme{hashtable-keys} and
 \endschemedisplay
 
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{hashtable-ephemeron?}{\categoryprocedure}{(hashtable-ephemeron? \var{obj})}
+\returns \scheme{#t} if \var{obj} is an ephemeron eq or eqv hashtable, \scheme{#f} otherwise
+\listlibraries
+\endentryheader
+
+\schemedisplay
+(define ht1 (make-ephemeron-eq-hashtable))
+(define ht2 (hashtable-copy ht1))
+(hashtable-ephemeron? ht2) ;=> #t
+\endschemedisplay
+
+
 %----------------------------------------------------------------------------
 \entryheader
 \formdef{eq-hashtable?}{\categoryprocedure}{(eq-hashtable? \var{obj})}
@@ -1904,6 +1948,20 @@ The effect of this can be observed via \scheme{hashtable-keys} and
 (eq-hashtable-weak? (make-weak-eq-hashtable)) ;=> #t
 \endschemedisplay
 
+%----------------------------------------------------------------------------
+\entryheader
+\formdef{eq-hashtable-ephemeron?}{\categoryprocedure}{(eq-hashtable-ephemeron? \var{hashtable})}
+\returns \scheme{#t} if \var{hashtable} uses ephemeron pairs, \scheme{#f} otherwise
+\listlibraries
+\endentryheader
+
+\var{hashtable} must be an eq hashtable.
+
+\schemedisplay
+(eq-hashtable-ephemeron? (make-eq-hashtable)) ;=> #f
+(eq-hashtable-ephemeron? (make-ephemeron-eq-hashtable)) ;=> #t
+\endschemedisplay
+
 %----------------------------------------------------------------------------
 \entryheader
 \formdef{eq-hashtable-set!}{\categoryprocedure}{(eq-hashtable-set! \var{hashtable} \var{key} \var{value})}
diff --git a/mats/hash.ms b/mats/hash.ms
index dcc77b45f9..38211f89b7 100644
--- a/mats/hash.ms
+++ b/mats/hash.ms
@@ -348,16 +348,22 @@
          (hashtable-mutable? $ht)
          (not (hashtable-weak? $ht))
          (not (eq-hashtable-weak? $ht))
+         (not (hashtable-ephemeron? $ht))
+         (not (eq-hashtable-ephemeron? $ht))
          (hashtable? $imht)
          (eq-hashtable? $imht)
          (not (hashtable-mutable? $imht))
          (not (hashtable-weak? $imht))
          (not (eq-hashtable-weak? $imht))
+         (not (hashtable-ephemeron? $imht))
+         (not (eq-hashtable-ephemeron? $imht))
          (hashtable? $ht2)
          (eq-hashtable? $ht2)
          (hashtable-mutable? $ht2)
          (not (hashtable-weak? $ht2))
-         (not (eq-hashtable-weak? $ht2))))
+         (not (eq-hashtable-weak? $ht2))
+         (not (hashtable-ephemeron? $ht2))
+         (not (eq-hashtable-ephemeron? $ht2))))
   (not (hashtable? 3))
   (not (hashtable? (make-vector 3)))
   (not (eq-hashtable? 3))
@@ -519,6 +525,13 @@
     (hashtable-weak? $ht 3))
   (error? ; not a hashtable
     (hashtable-weak? '(hash . table)))
+ ; hashtable-ephemeron?
+  (error? ; wrong argument count
+    (hashtable-ephemeron?))
+  (error? ; wrong argument count
+    (hashtable-ephemeron? $ht 3))
+  (error? ; not a hashtable
+    (hashtable-ephemeron? '(hash . table)))
 )
 
 (mat hash-return-value
@@ -612,25 +625,64 @@
     (make-weak-eq-hashtable #t))
   (error? ; invalid size
     (make-weak-eq-hashtable #f))
+ ; make-weak-eq-hashtable
+  (error? ; wrong argument count
+    (make-ephemeron-eq-hashtable 3 #t))
+  (error? ; invalid size
+    (make-ephemeron-eq-hashtable -1))
+  (error? ; invalid size
+    (make-ephemeron-eq-hashtable #t))
+  (error? ; invalid size
+    (make-ephemeron-eq-hashtable #f))
   (begin
     (define $wht (make-weak-eq-hashtable 50))
+    (define $eht (make-ephemeron-eq-hashtable 50))
     (define $imht (hashtable-copy $wht))
+    (define $imeht (hashtable-copy $eht))
     (define $wht2 (make-weak-eq-hashtable))
+    (define $eht2 (make-ephemeron-eq-hashtable))
     (and (hashtable? $wht)
+         (hashtable? $eht)
          (eq-hashtable? $wht)
+         (eq-hashtable? $eht)
          (hashtable-weak? $wht)
+         (not (hashtable-ephemeron? $wht))
+         (hashtable-ephemeron? $eht)
+         (not (hashtable-weak? $eht))
          (eq-hashtable-weak? $wht)
+         (not (eq-hashtable-ephemeron? $wht))
+         (eq-hashtable-ephemeron? $eht)
+         (not (eq-hashtable-weak? $eht))
          (hashtable-mutable? $wht)
+         (hashtable-mutable? $eht)
          (hashtable? $imht)
+         (hashtable? $imeht)
          (eq-hashtable? $imht)
+         (eq-hashtable? $imeht)
          (hashtable-weak? $imht)
+         (not (hashtable-ephemeron? $imht))
+         (hashtable-ephemeron? $imeht)
+         (not (hashtable-weak? $imeht))
          (eq-hashtable-weak? $imht)
+         (not (eq-hashtable-ephemeron? $imht))
+         (eq-hashtable-ephemeron? $imeht)
+         (not (eq-hashtable-weak? $imeht))
          (not (hashtable-mutable? $imht))
+         (not (hashtable-mutable? $imeht))
          (hashtable? $wht2)
+         (hashtable? $eht2)
          (eq-hashtable? $wht2)
+         (eq-hashtable? $eht2)
          (hashtable-weak? $wht2)
+         (not (hashtable-ephemeron? $wht2))
+         (hashtable-ephemeron? $eht2)
+         (not (hashtable-weak? $eht2))
          (eq-hashtable-weak? $wht2)
-         (hashtable-mutable? $wht2)))
+         (not (eq-hashtable-ephemeron? $ht2))
+         (eq-hashtable-ephemeron? $eht2)
+         (not (eq-hashtable-weak? $eht2))
+         (hashtable-mutable? $wht2)
+         (hashtable-mutable? $eht2)))
  ; eq-hashtable-ref
   (error? ; wrong argument count
     (eq-hashtable-ref))
@@ -708,6 +760,13 @@
     (eq-hashtable-weak? $ht 3))
   (error? ; not a hashtable
     (eq-hashtable-weak? '(hash . table)))
+ ; eq-hashtable-ephemeron?
+  (error? ; wrong argument count
+    (eq-hashtable-ephemeron?))
+  (error? ; wrong argument count
+    (eq-hashtable-ephemeron? $ht 3))
+  (error? ; not a hashtable
+    (eq-hashtable-ephemeron? '(hash . table)))
 )
 
 (mat symbol-hashtable-arguments
@@ -833,6 +892,15 @@
     (make-weak-eqv-hashtable #t))
   (error? ; invalid size
     (make-weak-eqv-hashtable #f))
+ ; make-ephemeron-eqv-hashtable
+  (error? ; wrong argument count
+    (make-ephemeron-eqv-hashtable 3 #t))
+  (error? ; invalid size
+    (make-ephemeron-eqv-hashtable -1))
+  (error? ; invalid size
+    (make-ephemeron-eqv-hashtable #t))
+  (error? ; invalid size
+    (make-ephemeron-eqv-hashtable #f))
 )
 
 (mat nonweak-eq-hashtable
@@ -842,7 +910,9 @@
          (eq-hashtable? h)
          (hashtable-mutable? h)
          (not (eq-hashtable-weak? h))
-         (not (hashtable-weak? h))))
+         (not (eq-hashtable-ephemeron? h))
+         (not (hashtable-weak? h))
+         (not (hashtable-ephemeron? h))))
   (eq? (hashtable-hash-function h) #f)
   (eq? (hashtable-equivalence-function h) eq?)
   (equal? (hashtable-size h) 0)
@@ -899,7 +969,9 @@
          (eq-hashtable? h2)
          (hashtable-mutable? h2)
          (not (hashtable-weak? h2))
-         (not (eq-hashtable-weak? h2))))
+         (not (eq-hashtable-weak? h2))
+         (not (hashtable-ephemeron? h2))
+         (not (eq-hashtable-ephemeron? h2))))
   (eq? (hashtable-hash-function h2) #f)
   (eq? (hashtable-equivalence-function h2) eq?)
   (equal? (hashtable-size h2) 2)
@@ -1174,8 +1246,7 @@
       (list (hashtable-size ht) (= (#%$hashtable-veclen ht) len)))
     '(0 #t))
 
-  ; test that weak-hashtable values do not imply that values
-  ; are reachable
+  ; test that weak-hashtable values *do* make keys reachable
   (let ([wk1 (list 1)]
         [wk2 (list 2)]
         [wk3 (list 3)]
@@ -1186,6 +1257,242 @@
     (hashtable-set! ht wk3 wk3)
     (hashtable-set! ht wk4 wk2)
     (collect (collect-maximum-generation))
+    (and
+     (same-elements? (hashtable-keys ht) '#((1) (2) (3) (4)))
+     (equal? (hashtable-ref ht wk1 #f) wk1)
+     (equal? (hashtable-ref ht wk2 #f) wk1)
+     (equal? (hashtable-ref ht wk3 #f) wk3)
+     (equal? (hashtable-ref ht wk4 #f) wk2)
+     (begin
+       (set! wk1 #f)
+       (set! wk2 #f)
+       (set! wk3 #f)
+       (collect (collect-maximum-generation))
+       (and
+        (same-elements? (hashtable-keys ht) '#((1) (2) (3) (4)))
+        (equal? (hashtable-ref ht wk4 #f) '(2))
+        (begin
+          (set! wk4 #f)
+          (collect (collect-maximum-generation))
+          (same-elements? (hashtable-keys ht) '#((1) (2) (3))))))))
+)
+
+(mat ephemeron-eq-hashtable
+  (begin
+    (define ka (list 'a)) ; will map to self  \ Doesn't do anything to check
+    (define kb (list 'b)) ; will map to kc \  | ephemeronness, but just in
+    (define kc (list 'c)) ; will map to kb /  / case.
+    (define kq (list 'q))
+    (define ky (list 'y))
+    (define kz (list 'z))
+    #t)
+  (begin
+    (define h (make-ephemeron-eq-hashtable 32))
+    (and (hashtable? h)
+         (eq-hashtable? h)
+         (hashtable-mutable? h)
+         (hashtable-ephemeron? h)
+         (eq-hashtable-ephemeron? h)))
+  (eq? (hashtable-hash-function h) #f)
+  (eq? (hashtable-equivalence-function h) eq?)
+  (equal? (hashtable-size h) 0)
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  (eqv? (hashtable-set! h ka ka) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc))
+    '(#t #f #f))
+  (eqv? (hashtable-set! h kb kc) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc))
+    '(#t #t #f))
+  (eqv? (hashtable-set! h kc kb) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc))
+    '(#t #t #t))
+  (equal? (hashtable-size h) 3)
+  (same-elements? (hashtable-keys h) '#((a) (b) (c)))
+  (same-elements? (hashtable-values h) '#((a) (b) (c)))
+  (equal-entries? (hashtable-entries h) '#((a) (b) (c)) '#((a) (c) (b)))
+  #;(same-elements? (list->vector (hashtable-map h cons)) '#(((a) . a) ((b) . c) ((c) . b)))
+  #;(same-elements?
+    (let ([v (make-vector 3)] [i 0])
+      (hashtable-for-each h (lambda (key val) (vector-set! v i (cons key val)) (set! i (fx+ i 1))))
+      v)
+    '#(((a) . a) ((b) . c) ((c) . b)))
+  #;(same-elements?
+    (let ([v (make-vector 3)] [i 0])
+      (hashtable-for-each-cell h (lambda (a) (vector-set! v i a) (set! i (fx+ i 1))))
+      v)
+    '#(((a) . a) ((b) . c) ((c) . b)))
+  (equal? (hashtable-ref h ka 1) '(a))
+  (equal? (hashtable-ref h kb #f) '(c))
+  (equal? (hashtable-ref h kc 'nope) '(b))
+  (eqv? (hashtable-delete! h kb) (void))
+  (equal? (hashtable-size h) 2)
+  (same-elements? (hashtable-keys h) '#((a) (c)))
+  (same-elements? (hashtable-values h) '#((a) (b)))
+  (equal-entries? (hashtable-entries h) '#((a) (c)) '#((a) (b)))
+  (begin
+    (define h2 (hashtable-copy h #t))
+    (and (hashtable? h2)
+         (eq-hashtable? h2)
+         (hashtable-mutable? h2)
+         (eq-hashtable-ephemeron? h2)
+         (hashtable-ephemeron? h2)))
+  (eq? (hashtable-hash-function h2) #f)
+  (eq? (hashtable-equivalence-function h2) eq?)
+  (equal? (hashtable-size h2) 2)
+  (same-elements? (hashtable-keys h2) '#((a) (c)))
+  (same-elements? (hashtable-values h2) '#((a) (b)))
+  (equal-entries? (hashtable-entries h2) '#((a) (c)) '#((a) (b)))
+  (eqv? (hashtable-clear! h 4) (void))
+  (equal?
+    (list
+      (hashtable-size h)
+      (hashtable-ref h ka 1)
+      (hashtable-ref h kb #f)
+      (hashtable-ref h kc 'nope))
+   '(0 1 #f nope))
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  (equal?
+    (list
+      (hashtable-size h2)
+      (hashtable-ref h2 ka 1)
+      (hashtable-ref h2 kb #f)
+      (hashtable-ref h2 kc 'nope))
+    '(2 (a) #f (b)))
+  (same-elements? (hashtable-keys h2) '#((a) (c)))
+  (same-elements? (hashtable-values h2) '#((a) (b)))
+  (equal-entries? (hashtable-entries h2) '#((a) (c)) '#((a) (b)))
+  (eqv?
+    (hashtable-update! h kq
+      (lambda (x) (+ x 1))
+      17)
+    (void))
+  (equal? (hashtable-ref h kq #f) 18)
+  (eqv?
+    (hashtable-update! h kq
+      (lambda (x) (+ x 1))
+      17)
+    (void))
+  (equal? (hashtable-ref h kq #f) 19)
+  (equal? (hashtable-size h) 1)
+  (same-elements? (hashtable-keys h) '#((q)))
+  (same-elements? (hashtable-values h) '#(19))
+  (eqv?
+    (begin
+      (set! kq (void))
+      (collect (collect-maximum-generation))
+      (hashtable-size h))
+    0)
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  #;(eqv? (hashtable-map h (lambda args (error #f "oops"))) '())
+  #;(eqv? (hashtable-for-each h (lambda args (error #f "oops"))) (void))
+  #;(eqv? (hashtable-for-each-cell h (lambda args (error #f "oops"))) (void))
+  (equal? (hashtable-ref h ky #f) #f)
+  (eqv?
+    (hashtable-set! h ky 'toad)
+    (void))
+  (equal? (hashtable-ref h ky #f) 'toad)
+  (equal? (hashtable-ref h kz #f) #f)
+  (eqv?
+    (hashtable-update! h kz list 'frog)
+    (void))
+  (equal? (hashtable-ref h kz #f) '(frog))
+  (same-elements? (hashtable-keys h) (vector ky kz))
+  (same-elements? (hashtable-values h) (vector (hashtable-ref h kz #f) 'toad))
+  (equal-entries?
+    (hashtable-entries h)
+    (vector kz ky)
+    (vector (hashtable-ref h kz #f) 'toad))
+  (eqv? (hashtable-ref h '(zippo) 'nil) 'nil)
+  (begin
+    (define h3 (hashtable-copy h2 #f))
+    (and (hashtable? h3)
+         (eq-hashtable? h3)
+         (not (hashtable-mutable? h3))
+         (eq-hashtable-ephemeron? h3)
+         (hashtable-ephemeron? h3)))
+  (same-elements? (hashtable-keys h2) '#((a) (c)))
+  (same-elements? (hashtable-keys h3) '#((a) (c)))
+  (same-elements? (hashtable-values h2) '#((a) (b)))
+  (same-elements? (hashtable-values h3) '#((a) (b)))
+  (equal?
+    (begin
+      (set! ka (void))
+      (collect (collect-maximum-generation))
+      (list (hashtable-size h2) (hashtable-size h3)))
+    '(1 1))
+  (same-elements? (hashtable-keys h2) '#((c)))
+  (same-elements? (hashtable-keys h3) '#((c)))
+  (same-elements? (hashtable-values h2) '#((b)))
+  (same-elements? (hashtable-values h3) '#((b)))
+  (equal-entries? (hashtable-entries h2) '#((c)) '#((b)))
+  (equal-entries? (hashtable-entries h3) '#((c)) '#((b)))
+  (eqv?
+    (begin
+      (set! h3 (void))
+      (collect (collect-maximum-generation))
+      (hashtable-size h2))
+    1)
+  (same-elements? (hashtable-keys h2) '#((c)))
+  (same-elements? (hashtable-values h2) '#((b)))
+  (equal-entries? (hashtable-entries h2) '#((c)) '#((b)))
+
+ ; test for proper shrinkage
+  (eqv?
+    (let ([ht (make-eq-hashtable 32)])
+      (for-each
+        (lambda (k*) (for-each (lambda (k) (hashtable-delete! ht k)) k*))
+        (let ([k** (map (lambda (x) (map list (make-list 1000)))
+                        (make-list 100))])
+          (for-each
+            (lambda (k*) (map (lambda (k) (hashtable-set! ht k 75)) k*))
+            k**)
+          k**))
+      (#%$hashtable-veclen ht))
+    32)
+
+ ; test for proper shrinkage as objects are bwp'd
+ ; uses delete to trigger final shrinkage
+  (equal?
+    (let* ([ht (make-ephemeron-eq-hashtable 32)]
+           [len (#%$hashtable-veclen ht)])
+      (hashtable-set! ht 'a 'b)
+      (for-each
+        (lambda (k*) (map (lambda (k) (hashtable-set! ht k 75)) k*))
+        (map (lambda (x) (map list (make-list 1000))) (make-list 100)))
+      (collect (collect-maximum-generation))
+      (hashtable-delete! ht 'a)
+      (list (hashtable-size ht) (= (#%$hashtable-veclen ht) len)))
+    '(0 #t))
+
+  ; test that ephemeron-hashtable values don't make keys reachable
+  (let ([wk1 (list 1)]
+        [wk2 (list 2)]
+        [wk3 (list 3)]
+        [wk4 (list 4)]
+        [ht (make-ephemeron-eq-hashtable)])
+    (hashtable-set! ht wk1 wk1)
+    (hashtable-set! ht wk2 wk1)
+    (hashtable-set! ht wk3 wk3)
+    (hashtable-set! ht wk4 wk2)
+    (collect (collect-maximum-generation))
     (and
      (same-elements? (hashtable-keys ht) '#((1) (2) (3) (4)))
      (equal? (hashtable-ref ht wk1 #f) wk1)
@@ -1228,19 +1535,28 @@
                        (cons (random-object 4) (random-object 7))
                        (f (fx- n 1)))))]
           [ht (make-eq-hashtable)]
-          [wht (make-weak-eq-hashtable)])
+          [wht (make-weak-eq-hashtable)]
+          [eht (make-ephemeron-eq-hashtable)])
       (let ([ls2 (map (lambda (a1) (eq-hashtable-cell ht (car a1) (cdr a1))) ls1)]
-            [ls3 (map (lambda (a1) (hashtable-cell wht (car a1) (cdr a1))) ls1)])
-        (unless (andmap (lambda (a1 a2 a3)
+            [ls3 (map (lambda (a1) (hashtable-cell wht (car a1) (cdr a1))) ls1)]
+            [ls4 (map (lambda (a1) (hashtable-cell eht (car a1) (cdr a1))) ls1)])
+        (unless (andmap (lambda (a1 a2 a3 a4)
                           (and (eq? (car a1) (car a2))
-                               (eq? (car a2) (car a3))))
-                        ls1 ls2 ls3)
+                               (eq? (car a2) (car a3))
+                               (eq? (car a2) (car a4))))
+                        ls1 ls2 ls3 ls4)
           (errorf #f "keys are not eq"))
-        (unless (andmap (lambda (a1 a2 a3)
+        (unless (andmap (lambda (a1 a2 a3 a4)
                           (and (eq? (cdr a1) (cdr a2))
-                               (eq? (cdr a2) (cdr a3))))
-                        ls1 ls2 ls3)
+                               (eq? (cdr a2) (cdr a3))
+                               (eq? (cdr a2) (cdr a4))))
+                        ls1 ls2 ls3 ls4)
           (errorf #f "values are not eq"))
+        (for-each (lambda (a1)
+                    (let ([o (random-object 3)])
+                      ;; Value refers to key:
+                      (hashtable-set! eht o (list o (car a1)))))
+                  ls1)
         (for-each
           (lambda (a1)
             (when (fx< (random 10) 5)
@@ -1249,9 +1565,11 @@
         (let loop ([i (min (expt (collect-generation-radix) (collect-maximum-generation)) 1000)])
           (unless (fx= i 0)
             (collect)
-            (unless (andmap (lambda (a2 a3) (eq? (car a2) (car a3))) ls2 ls3)
-              (errorf #f "a2/a3 keys not eq after collection"))
-            (unless (andmap (lambda (a3) (not (bwp-object? (car a3)))) ls3)
+            (unless (andmap (lambda (a2 a3 a4) (and (eq? (car a2) (car a3)) (eq? (car a2) (car a4))))
+                            ls2 ls3 ls4)
+              (errorf #f "a2/a3/a4 keys not eq after collection"))
+            (unless (and (andmap (lambda (a3) (not (bwp-object? (car a3)))) ls3)
+                         (andmap (lambda (a4) (not (bwp-object? (car a4)))) ls4))
               (errorf #f "keys have been bwp'd"))
             (loop (fx- i 1))))
         (for-each
@@ -1262,28 +1580,37 @@
         (unless (and (equal? (hashtable-keys ht) '#())
                      (equal? (hashtable-values ht) '#())
                      (zero? (hashtable-size ht)))
-          (errorf #f "wht has not been cleared out"))
+          (errorf #f "ht has not been cleared out"))
         (let loop ([i (min (expt (collect-generation-radix) (collect-maximum-generation)) 1000)])
           (unless (fx= i 0)
             (collect)
-            (unless (andmap (lambda (a1 a3)
-                              (or (not (car a1)) (eq? (car a1) (car a3))))
-                            ls1 ls3)
-              (errorf #f "a1/a3 keys not eq after collection"))
+            (unless (andmap (lambda (a1 a3 a4)
+                              (or (not (car a1))
+                                  (and (eq? (car a1) (car a3))
+                                       (eq? (car a1) (car a4)))))
+                            ls1 ls3 ls4)
+              (errorf #f "a1/a3/a4 keys not eq after collection"))
             (loop (fx- i 1))))
         (for-each
-          (lambda (a1 a3)
-            (unless (or (car a1) (bwp-object? (car a3)))
+          (lambda (a1 a3 a4)
+            (unless (or (car a1)
+                        (and (bwp-object? (car a3))
+                             (bwp-object? (car a4))))
               (errorf #f "~s has not been bwp'd I" (car a3))))
-          ls1 ls3)
+          ls1 ls3 ls4)
         (for-each (lambda (a1) (set-car! a1 #f)) ls1)
         (collect (collect-maximum-generation))
-        (unless (andmap (lambda (a3) (bwp-object? (car a3))) ls3)
+        (unless (and (andmap (lambda (a3) (bwp-object? (car a3))) ls3)
+                     (andmap (lambda (a4) (bwp-object? (car a4))) ls4))
           (errorf #f "keys have not been bwp'd II"))
         (unless (and (equal? (hashtable-keys wht) '#())
                      (equal? (hashtable-values wht) '#())
-                     (zero? (hashtable-size ht)))
-          (errorf #f "wht has not been cleared out"))))
+                     (zero? (hashtable-size wht)))
+          (errorf #f "wht has not been cleared out"))
+        (unless (and (equal? (hashtable-keys eht) '#())
+                     (equal? (hashtable-values eht) '#())
+                     (zero? (hashtable-size eht)))
+          (errorf #f "eht has not been cleared out"))))
     #t)
 )
 
@@ -1294,7 +1621,9 @@
          (eq-hashtable? h)
          (hashtable-mutable? h)
          (not (eq-hashtable-weak? h))
-         (not (hashtable-weak? h))))
+         (not (hashtable-weak? h))
+         (not (eq-hashtable-ephemeron? h))
+         (not (hashtable-ephemeron? h))))
   (eq? (hashtable-hash-function h) #f)
   (eq? (hashtable-equivalence-function h) eq?)
   (equal? (hashtable-size h) 0)
@@ -1611,24 +1940,221 @@
       (eq-hashtable-delete! ht 'a)
       (list (hashtable-size ht) (= (#%$hashtable-veclen ht) len)))
     '(0 #t))
+  )
+
+(mat $ephemeron-eq-hashtable
+  (begin
+    (define ka (list 'a))
+    (define kb (list 'b))
+    (define kc (list 'c))
+    (define kq (list 'q))
+    (define ky (list 'y))
+    (define kz (list 'z))
+    #t)
+  (begin
+    (define h (make-ephemeron-eq-hashtable 32))
+    (and (hashtable? h)
+         (eq-hashtable? h)
+         (hashtable-mutable? h)
+         (eq-hashtable-ephemeron? h)
+         (hashtable-ephemeron? h)))
+  (eq? (hashtable-hash-function h) #f)
+  (eq? (hashtable-equivalence-function h) eq?)
+  (equal? (hashtable-size h) 0)
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  (eqv? (eq-hashtable-set! h ka 'aval) (void))
+  (equal?
+    (list
+       (eq-hashtable-contains? h ka)
+       (eq-hashtable-contains? h kb)
+       (eq-hashtable-contains? h kc))
+    '(#t #f #f))
+  (eqv? (eq-hashtable-set! h kb 'bval) (void))
+  (equal?
+    (list
+       (eq-hashtable-contains? h ka)
+       (eq-hashtable-contains? h kb)
+       (eq-hashtable-contains? h kc))
+    '(#t #t #f))
+  (eqv? (eq-hashtable-set! h kc 'cval) (void))
+  (equal?
+    (list
+       (eq-hashtable-contains? h ka)
+       (eq-hashtable-contains? h kb)
+       (eq-hashtable-contains? h kc))
+    '(#t #t #t))
+  (equal? (hashtable-size h) 3)
+  (same-elements? (hashtable-keys h) '#((a) (b) (c)))
+  (same-elements? (hashtable-values h) '#(aval bval cval))
+  (equal-entries? (hashtable-entries h) '#((a) (b) (c)) '#(aval bval cval))
+  (equal? (eq-hashtable-ref h ka 1) 'aval)
+  (equal? (eq-hashtable-ref h kb #f) 'bval)
+  (equal? (eq-hashtable-ref h kc 'nope) 'cval)
+  (eqv? (eq-hashtable-delete! h kb) (void))
+  (equal? (hashtable-size h) 2)
+  (same-elements? (hashtable-keys h) '#((a) (c)))
+  (same-elements? (hashtable-values h) '#(aval cval))
+  (equal-entries? (hashtable-entries h) '#((a) (c)) '#(aval cval))
+  (begin
+    (define h2 (hashtable-copy h #t))
+    (and (hashtable? h2)
+         (eq-hashtable? h2)
+         (hashtable-mutable? h2)
+         (hashtable-ephemeron? h2)
+         (eq-hashtable-ephemeron? h2)))
+  (equal? (hashtable-size h2) 2)
+  (same-elements? (hashtable-keys h2) '#((a) (c)))
+  (same-elements? (hashtable-values h2) '#(aval cval))
+  (equal-entries? (hashtable-entries h2) '#((a) (c)) '#(aval cval))
+  (eqv? (hashtable-clear! h 4) (void))
+  (equal?
+    (list
+      (hashtable-size h)
+      (eq-hashtable-ref h ka 1)
+      (eq-hashtable-ref h kb #f)
+      (eq-hashtable-ref h kc 'nope))
+   '(0 1 #f nope))
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  (equal?
+    (list
+      (hashtable-size h2)
+      (eq-hashtable-ref h2 ka 1)
+      (eq-hashtable-ref h2 kb #f)
+      (eq-hashtable-ref h2 kc 'nope))
+    '(2 aval #f cval))
+  (same-elements? (hashtable-keys h2) '#((a) (c)))
+  (same-elements? (hashtable-values h2) '#(aval cval))
+  (equal-entries? (hashtable-entries h2) '#((a) (c)) '#(aval cval))
+  (eqv?
+    (eq-hashtable-update! h kq
+      (lambda (x) (+ x 1))
+      17)
+    (void))
+  (equal? (eq-hashtable-ref h kq #f) 18)
+  (eqv?
+    (eq-hashtable-update! h kq
+      (lambda (x) (+ x 1))
+      17)
+    (void))
+  (equal? (eq-hashtable-ref h kq #f) 19)
+  (equal? (hashtable-size h) 1)
+  (same-elements? (hashtable-keys h) '#((q)))
+  (same-elements? (hashtable-values h) '#(19))
+  (eqv?
+    (begin
+      (set! kq (void))
+      (collect (collect-maximum-generation))
+      (hashtable-size h))
+    0)
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  (equal? (eq-hashtable-ref h ky #f) #f)
+  (eqv?
+    (eq-hashtable-set! h ky 'toad)
+    (void))
+  (equal? (eq-hashtable-ref h ky #f) 'toad)
+  (equal? (eq-hashtable-ref h kz #f) #f)
+  (eqv?
+    (eq-hashtable-update! h kz list 'frog)
+    (void))
+  (equal? (eq-hashtable-ref h kz #f) '(frog))
+  (same-elements? (hashtable-keys h) (vector ky kz))
+  (same-elements? (hashtable-values h) (vector (eq-hashtable-ref h kz #f) 'toad))
+  (equal-entries?
+    (hashtable-entries h)
+    (vector kz ky)
+    (vector (eq-hashtable-ref h kz #f) 'toad))
+  (eqv? (eq-hashtable-ref h '(zippo) 'nil) 'nil)
+  (begin
+    (define h3 (hashtable-copy h2 #f))
+    (and (hashtable? h3)
+         (eq-hashtable? h3)
+         (not (hashtable-mutable? h3))
+         (eq-hashtable-ephemeron? h3)
+         (hashtable-ephemeron? h3)))
+  (same-elements? (hashtable-keys h2) '#((a) (c)))
+  (same-elements? (hashtable-keys h3) '#((a) (c)))
+  (same-elements? (hashtable-values h2) '#(aval cval))
+  (same-elements? (hashtable-values h3) '#(aval cval))
+  (equal?
+    (begin
+      (set! ka (void))
+      (collect (collect-maximum-generation))
+      (list (hashtable-size h2) (hashtable-size h3)))
+    '(1 1))
+  (same-elements? (hashtable-keys h2) '#((c)))
+  (same-elements? (hashtable-keys h3) '#((c)))
+  (same-elements? (hashtable-values h2) '#(cval))
+  (same-elements? (hashtable-values h3) '#(cval))
+  (equal-entries? (hashtable-entries h2) '#((c)) '#(cval))
+  (equal-entries? (hashtable-entries h3) '#((c)) '#(cval))
+  (eqv?
+    (begin
+      (set! h3 (void))
+      (collect (collect-maximum-generation))
+      (hashtable-size h2))
+    1)
+  (same-elements? (hashtable-keys h2) '#((c)))
+  (same-elements? (hashtable-values h2) '#(cval))
+  (equal-entries? (hashtable-entries h2) '#((c)) '#(cval))
+
+ ; test for proper shrinkage
+  (eqv?
+    (let ([ht (make-eq-hashtable 32)])
+      (for-each
+        (lambda (k*) (for-each (lambda (k) (eq-hashtable-delete! ht k)) k*))
+        (let ([k** (map (lambda (x) (map list (make-list 1000)))
+                        (make-list 100))])
+          (for-each
+            (lambda (k*) (map (lambda (k) (eq-hashtable-set! ht k 75)) k*))
+            k**)
+          k**))
+      (#%$hashtable-veclen ht))
+    32)
+
+ ; test for proper shrinkage as objects are bwp'd
+ ; uses delete to trigger final shrinkage
+  (equal?
+    (let* ([ht (make-ephemeron-eq-hashtable 32)]
+           [len (#%$hashtable-veclen ht)])
+      (eq-hashtable-set! ht 'a 'b)
+      (for-each
+        (lambda (k*) (map (lambda (k) (eq-hashtable-set! ht k 75)) k*))
+        (map (lambda (x) (map list (make-list 1000))) (make-list 100)))
+      (collect (collect-maximum-generation))
+      (eq-hashtable-delete! ht 'a)
+      (list (hashtable-size ht) (= (#%$hashtable-veclen ht) len)))
+    '(0 #t))
 )
 
 (mat eq-strange
   (begin
     (define $ht (make-eq-hashtable))
     (define $wht (make-weak-eq-hashtable))
+    (define $eht (make-ephemeron-eq-hashtable))
     (and (hashtable? $ht)
          (eq-hashtable? $ht)
          (hashtable? $wht)
-         (eq-hashtable? $wht)))
+         (eq-hashtable? $wht)
+         (hashtable? $eht)
+         (eq-hashtable? $eht)))
   (eqv? (hashtable-set! $ht #f 75) (void))
   (eqv? (hashtable-ref $ht #f 80) 75)
   (eqv? (hashtable-set! $wht #f 75) (void))
   (eqv? (hashtable-ref $wht #f 80) 75)
+  (eqv? (hashtable-set! $eht #f 75) (void))
+  (eqv? (hashtable-ref $eht #f 80) 75)
   (eqv? (hashtable-set! $ht #!bwp "hello") (void))
   (equal? (hashtable-ref $ht #!bwp "goodbye") "hello")
   (eqv? (hashtable-set! $wht #!bwp "hello") (void))
   (and (member (hashtable-ref $wht #!bwp "goodbye") '("hello" "goodbye")) #t)
+  (eqv? (hashtable-set! $eht #!bwp "hello") (void))
+  (and (member (hashtable-ref $eht #!bwp "goodbye") '("hello" "goodbye")) #t)
  ; make sure that association isn't added before procedure is called
   (equal?
     (begin
@@ -1644,6 +2170,13 @@
         'doll)
       (hashtable-ref $wht 'cupie 'oops))
    '(barbie . doll))
+  (equal?
+    (begin
+      (hashtable-update! $eht 'cupie
+        (lambda (x) (hashtable-ref $eht 'cupie (cons 'barbie x)))
+        'doll)
+      (hashtable-ref $eht 'cupie 'oops))
+   '(barbie . doll))
 )
 
 (mat eq-hashtable-stress
@@ -1721,6 +2254,44 @@
                           (f (+ i 1) (remq k keep) drop)))
                       (f (+ i 1) keep drop)))))))))
 
+  (let () ; ephemeron
+    (define pick
+      (lambda (ls)
+        (list-ref ls (random (length ls)))))
+    (define ht (make-ephemeron-eq-hashtable 4))
+    (let ([ls (remq '|| (oblist))] [n 50000])
+      (let f ([i 0] [keep '()] [drop '()])
+        (if (= i n)
+            (and (<= (hashtable-size ht) (- n (length drop)))
+                 (begin
+                   (collect (collect-maximum-generation))
+                   (= (hashtable-size ht) (length keep)))
+                 (andmap (lambda (k)
+                           (string=?
+                             (symbol->string (hashtable-ref ht k #f))
+                             (cond
+                               [(string? k) k]
+                               [(pair? k) (car k)]
+                               [(vector? k) (vector-ref k 0)])))
+                         keep)
+                 (andmap (lambda (k) (eq? (hashtable-ref ht k 'no) 'no))
+                         drop))
+            (let* ([x (pick ls)] [s (string-copy (symbol->string x))])
+              (let ([k (case (pick '(string pair vector))
+                         [(string) s]
+                         [(pair) (list s)]
+                         [(vector) (vector s)])])
+                (hashtable-set! ht k x)
+                (let ([keep (if (= (modulo i 5) 0) (cons k keep) keep)])
+                  (if (= (modulo i 17) 5)
+                      (let ([k (pick keep)])
+                        (hashtable-delete! ht k)
+                        (let ([drop (cons k drop)])
+                          (when (= (random 5) 3)
+                            (hashtable-delete! ht (pick drop)))
+                          (f (+ i 1) (remq k keep) drop)))
+                      (f (+ i 1) keep drop)))))))))
+
 )
 
 (mat nonweak-eqv-hashtable
@@ -1729,7 +2300,8 @@
     (and (hashtable? h)
          (not (eq-hashtable? h))
          (hashtable-mutable? h)
-         (not (hashtable-weak? h))))
+         (not (hashtable-weak? h))
+         (not (hashtable-ephemeron? h))))
   (eq? (hashtable-hash-function h) #f)
   (eq? (hashtable-equivalence-function h) eqv?)
   (equal? (hashtable-size h) 0)
@@ -1784,7 +2356,8 @@
     (define h2 (hashtable-copy h #t))
     (and (hashtable? h2)
          (hashtable-mutable? h2)
-         (not (hashtable-weak? h2))))
+         (not (hashtable-weak? h2))
+         (not (hashtable-ephemeron? h2))))
   (eq? (hashtable-hash-function h2) #f)
   (eq? (hashtable-equivalence-function h2) eqv?)
   (equal? (hashtable-size h2) 2)
@@ -2104,6 +2677,258 @@
             (let-values ([(n1 n2) (#%$hashtable-veclen ht)])
               (= n1 n2 32))))
     '(0 #t))
+  )
+
+(mat ephemeron-eqv-hashtable
+  (begin
+    (define ka (list 'a))
+    (define kb (list 'b))
+    (define kc (list 'c))
+    (define kq (list 'q))
+    (define ky (list 'y))
+    (define kz (list 'z))
+    (define km -5.75)
+    (define kn 17)
+    (define ko (+ (most-positive-fixnum) 5))
+    #t)
+  (begin
+    (define h (make-ephemeron-eqv-hashtable 32))
+    (and (hashtable? h)
+         (not (eq-hashtable? h))
+         (hashtable-mutable? h)
+         (hashtable-ephemeron? h)))
+  (eq? (hashtable-hash-function h) #f)
+  (eq? (hashtable-equivalence-function h) eqv?)
+  (equal? (hashtable-size h) 0)
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  (eqv? (hashtable-set! h ka 'aval) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc)
+       (hashtable-contains? h km)
+       (hashtable-contains? h kn)
+       (hashtable-contains? h ko))
+    '(#t #f #f #f #f #f))
+  (eqv? (hashtable-set! h kb 'bval) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc)
+       (hashtable-contains? h km)
+       (hashtable-contains? h kn)
+       (hashtable-contains? h ko))
+    '(#t #t #f #f #f #f))
+  (eqv? (hashtable-set! h kc 'cval) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc)
+       (hashtable-contains? h km)
+       (hashtable-contains? h kn)
+       (hashtable-contains? h ko))
+    '(#t #t #t #f #f #f))
+  (eqv? (hashtable-set! h km 'mval) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc)
+       (hashtable-contains? h km)
+       (hashtable-contains? h kn)
+       (hashtable-contains? h ko))
+    '(#t #t #t #t #f #f))
+  (eqv? (hashtable-set! h kn 'nval) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc)
+       (hashtable-contains? h km)
+       (hashtable-contains? h kn)
+       (hashtable-contains? h ko))
+    '(#t #t #t #t #t #f))
+  (eqv? (hashtable-set! h ko 'oval) (void))
+  (equal?
+    (list
+       (hashtable-contains? h ka)
+       (hashtable-contains? h kb)
+       (hashtable-contains? h kc)
+       (hashtable-contains? h km)
+       (hashtable-contains? h kn)
+       (hashtable-contains? h ko))
+    '(#t #t #t #t #t #t))
+  (equal? (hashtable-size h) 6)
+  (same-elements? (hashtable-keys h) `#((a) (b) (c) -5.75 17 ,ko))
+  (same-elements? (hashtable-values h) '#(aval bval cval mval nval oval))
+  (equal-entries? (hashtable-entries h) `#((a) (b) (c) -5.75 17 ,ko) '#(aval bval cval mval nval oval))
+  #;(same-elements?
+    (list->vector (hashtable-map h cons))
+    `#(((a) . aval) ((b) . bval) ((c) . cval) (-5.75 . mval) (17 . nval) (,ko . oval)))
+  #;(same-elements?
+    (let ([v (make-vector 6)] [i 0])
+      (hashtable-for-each h (lambda (key val) (vector-set! v i (cons key val)) (set! i (fx+ i 1))))
+      v)
+    `#(((a) . aval) ((b) . bval) ((c) . cval) (-5.75 . mval) (17 . nval) (,ko . oval)))
+  #;(same-elements?
+    (let ([v (make-vector 6)] [i 0])
+      (hashtable-for-each-cell h (lambda (a) (vector-set! v i a) (set! i (fx+ i 1))))
+      v)
+    `#(((a) . aval) ((b) . bval) ((c) . cval) (-5.75 . mval) (17 . nval) (,ko . oval)))
+  (eq? (hashtable-ref h ka 1) 'aval)
+  (eq? (hashtable-ref h kb #f) 'bval)
+  (eq? (hashtable-ref h kc 'nope) 'cval)
+  (eq? (hashtable-ref h (+ 2 -7.75) 'ugh) 'mval)
+  (eq? (hashtable-ref h (/ 34 2) 'ugh) 'nval)
+  (eq? (hashtable-ref h (+ (most-positive-fixnum) 7 -2) 'ugh) 'oval)
+  (eqv? (hashtable-delete! h kb) (void))
+  (equal? (hashtable-size h) 5)
+  (same-elements? (hashtable-keys h) `#((a) (c) -5.75 17 ,ko))
+  (same-elements? (hashtable-values h) '#(aval cval mval nval oval))
+  (equal-entries? (hashtable-entries h)  `#((a) (c) -5.75 17 ,ko) '#(aval cval mval nval oval))
+  (begin
+    (define h2 (hashtable-copy h #t))
+    (and (hashtable? h2)
+         (hashtable-mutable? h2)
+         (hashtable-ephemeron? h2)))
+  (eq? (hashtable-hash-function h2) #f)
+  (eq? (hashtable-equivalence-function h2) eqv?)
+  (equal? (hashtable-size h2) 5)
+  (same-elements? (hashtable-keys h) `#((a) (c) -5.75 17 ,ko))
+  (same-elements? (hashtable-values h) '#(aval cval mval nval oval))
+  (equal-entries? (hashtable-entries h)  `#((a) (c) -5.75 17 ,ko) '#(aval cval mval nval oval))
+  (eqv? (hashtable-clear! h 4) (void))
+  (equal?
+    (list
+      (hashtable-size h)
+      (hashtable-ref h ka 1)
+      (hashtable-ref h kb #f)
+      (hashtable-ref h kc 'nope)
+      (hashtable-ref h km 'nope)
+      (hashtable-ref h kn 'nope)
+      (hashtable-ref h ko 'nope))
+   '(0 1 #f nope nope nope nope))
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  (equal?
+    (list
+      (hashtable-size h2)
+      (hashtable-ref h2 ka 1)
+      (hashtable-ref h2 kb #f)
+      (hashtable-ref h2 kc 'nope)
+      (hashtable-ref h2 (- (+ km 1) 1) 'nope)
+      (hashtable-ref h2 (- (+ kn 1) 1) 'nope)
+      (hashtable-ref h2 (- (+ ko 1) 1) 'nope))
+    '(5 aval #f cval mval nval oval))
+  (same-elements? (hashtable-keys h2) `#((a) (c) -5.75 17 ,ko))
+  (same-elements? (hashtable-values h2) '#(aval cval mval nval oval))
+  (equal-entries? (hashtable-entries h2)  `#((a) (c) -5.75 17 ,ko) '#(aval cval mval nval oval))
+  (eqv?
+    (hashtable-update! h kq
+      (lambda (x) (+ x 1))
+      17)
+    (void))
+  (equal? (hashtable-ref h kq #f) 18)
+  (eqv?
+    (hashtable-update! h kq
+      (lambda (x) (+ x 1))
+      17)
+    (void))
+  (equal? (hashtable-ref h kq #f) 19)
+  (equal? (hashtable-size h) 1)
+  (same-elements? (hashtable-keys h) '#((q)))
+  (eqv?
+    (begin
+      (set! kq (void))
+      (collect (collect-maximum-generation))
+      (hashtable-size h))
+    0)
+  (same-elements? (hashtable-keys h) '#())
+  (same-elements? (hashtable-values h) '#())
+  (equal-entries? (hashtable-entries h) '#() '#())
+  (equal? (hashtable-ref h ky #f) #f)
+  (eqv?
+    (hashtable-set! h ky 'toad)
+    (void))
+  (equal? (hashtable-ref h ky #f) 'toad)
+  (equal? (hashtable-ref h kz #f) #f)
+  (eqv?
+    (hashtable-update! h kz list 'frog)
+    (void))
+  (equal? (hashtable-ref h kz #f) '(frog))
+  (same-elements? (hashtable-keys h) (vector ky kz))
+  (same-elements? (hashtable-values h) (vector (hashtable-ref h kz #f) 'toad))
+  (equal-entries?
+    (hashtable-entries h)
+    (vector kz ky)
+    (vector (hashtable-ref h kz #f) 'toad))
+  (eqv? (hashtable-ref h '(zippo) 'nil) 'nil)
+  (begin
+    (define h3 (hashtable-copy h2 #f))
+    (and (hashtable? h3)
+         (not (hashtable-mutable? h3))
+         (hashtable-ephemeron? h3)))
+  (same-elements? (hashtable-keys h2) `#((a) (c) -5.75 17 ,ko))
+  (same-elements? (hashtable-keys h3) `#((a) (c) -5.75 17 ,ko))
+  (equal?
+    (begin
+      (set! ka (void))
+      (set! km (void))
+      (set! kn (void))
+      (set! ko (void))
+      (collect (collect-maximum-generation))
+      (list (hashtable-size h2) (hashtable-size h3)))
+    '(4 4))
+  (same-elements? (hashtable-keys h2) `#((c) -5.75 17 ,(+ (most-positive-fixnum) 5)))
+  (same-elements? (hashtable-keys h3) `#((c) -5.75 17 ,(+ (most-positive-fixnum) 5)))
+  (same-elements? (hashtable-values h2) '#(cval mval nval oval))
+  (same-elements? (hashtable-values h3) '#(cval mval nval oval))
+  (equal-entries? (hashtable-entries h2)  `#((c) -5.75 17 ,(+ (most-positive-fixnum) 5)) '#(cval mval nval oval))
+  (equal-entries? (hashtable-entries h3)  `#((c) -5.75 17 ,(+ (most-positive-fixnum) 5)) '#(cval mval nval oval))
+  (eqv?
+    (begin
+      (set! h3 (void))
+      (collect (collect-maximum-generation))
+      (hashtable-size h2))
+    4)
+  (same-elements? (hashtable-keys h2) `#((c) -5.75 17 ,(+ (most-positive-fixnum) 5)))
+  (same-elements? (hashtable-values h2) '#(cval mval nval oval))
+  (equal-entries? (hashtable-entries h2)  `#((c) -5.75 17 ,(+ (most-positive-fixnum) 5)) '#(cval mval nval oval))
+
+ ; test for proper shrinkage
+  (equal?
+    (let ([ht (make-eqv-hashtable 32)])
+      (for-each
+        (lambda (k*) (for-each (lambda (k) (hashtable-delete! ht k)) k*))
+        (let ([k** (map (lambda (x) (map list (make-list 1000)))
+                        (make-list 100))])
+          (for-each
+            (lambda (k*) (map (lambda (k) (hashtable-set! ht k 75)) k*))
+            k**)
+          k**))
+      (call-with-values (lambda () (#%$hashtable-veclen ht)) cons))
+    '(32 . 32))
+
+ ; test for proper shrinkage as objects are bwp'd
+ ; uses delete to trigger final shrinkage
+  (equal?
+    (let ([ht (make-ephemeron-eqv-hashtable 32)])
+      (hashtable-set! ht 'a 'b)
+      (for-each
+        (lambda (k*) (map (lambda (k) (hashtable-set! ht k 75)) k*))
+        (map (lambda (x) (map list (make-list 1000))) (make-list 100)))
+      (collect (collect-maximum-generation))
+      (hashtable-delete! ht 'a)
+      (list (hashtable-size ht)
+            (let-values ([(n1 n2) (#%$hashtable-veclen ht)])
+              (= n1 n2 32))))
+    '(0 #t))
 )
 
 (mat eqv-hashtable-cell
@@ -2128,19 +2953,28 @@
                        (cons (random-object 4) (random-object 7))
                        (f (fx- n 1)))))]
           [ht (make-eqv-hashtable)]
-          [wht (make-weak-eqv-hashtable)])
+          [wht (make-weak-eqv-hashtable)]
+          [eht (make-ephemeron-eqv-hashtable)])
       (let ([ls2 (map (lambda (a1) (hashtable-cell ht (car a1) (cdr a1))) ls1)]
-            [ls3 (map (lambda (a1) (hashtable-cell wht (car a1) (cdr a1))) ls1)])
-        (unless (andmap (lambda (a1 a2 a3)
+            [ls3 (map (lambda (a1) (hashtable-cell wht (car a1) (cdr a1))) ls1)]
+            [ls4 (map (lambda (a1) (hashtable-cell eht (car a1) (cdr a1))) ls1)])
+        (unless (andmap (lambda (a1 a2 a3 a4)
                           (and (eqv? (car a1) (car a2))
-                               (eqv? (car a2) (car a3))))
-                        ls1 ls2 ls3)
+                               (eqv? (car a2) (car a3))
+                               (eqv? (car a2) (car a4))))
+                        ls1 ls2 ls3 ls4)
           (errorf #f "keys are not eqv"))
-        (unless (andmap (lambda (a1 a2 a3)
+        (unless (andmap (lambda (a1 a2 a3 a4)
                           (and (eqv? (cdr a1) (cdr a2))
-                               (eqv? (cdr a2) (cdr a3))))
-                        ls1 ls2 ls3)
+                               (eqv? (cdr a2) (cdr a3))
+                               (eqv? (cdr a2) (cdr a4))))
+                        ls1 ls2 ls3 ls4)
           (errorf #f "values are not eqv"))
+        (for-each (lambda (a1)
+                    (let ([o (random-object 3)])
+                      ;; Value refers to key:
+                      (hashtable-set! eht o (list o (car a1)))))
+                  ls1)
         (for-each
           (lambda (a1)
             (when (fx< (random 10) 5)
@@ -2149,9 +2983,11 @@
         (let loop ([i (min (expt (collect-generation-radix) (collect-maximum-generation)) 1000)])
           (unless (fx= i 0)
             (collect)
-            (unless (andmap (lambda (a2 a3) (eqv? (car a2) (car a3))) ls2 ls3)
-              (errorf #f "a2/a3 keys not eqv after collection"))
-            (unless (andmap (lambda (a3) (not (bwp-object? (car a3)))) ls3)
+            (unless (andmap (lambda (a2 a3 a4) (and (eqv? (car a2) (car a3)) (eqv? (car a2) (car a4))))
+                            ls2 ls3 ls4)
+              (errorf #f "a2/a3/a4 keys not eqv after collection"))
+            (unless (and (andmap (lambda (a3) (not (bwp-object? (car a3)))) ls3)
+                         (andmap (lambda (a4) (not (bwp-object? (car a4)))) ls4))
               (errorf #f "keys have been bwp'd"))
             (loop (fx- i 1))))
         (for-each
@@ -2162,45 +2998,60 @@
         (unless (and (equal? (hashtable-keys ht) '#())
                      (equal? (hashtable-values ht) '#())
                      (zero? (hashtable-size ht)))
-          (errorf #f "wht has not been cleared out"))
+          (errorf #f "ht has not been cleared out"))
         (let loop ([i (min (expt (collect-generation-radix) (collect-maximum-generation)) 1000)])
           (unless (fx= i 0)
             (collect)
-            (unless (andmap (lambda (a1 a3)
-                              (or (not (car a1)) (eqv? (car a1) (car a3))))
-                            ls1 ls3)
-              (errorf #f "a1/a3 keys not eqv after collection"))
+            (unless (andmap (lambda (a1 a3 a4)
+                              (or (not (car a1))
+                                  (and (eqv? (car a1) (car a3))
+                                       (eqv? (car a1) (car a4)))))
+                            ls1 ls3 ls4)
+              (errorf #f "a1/a3/a4 keys not eqv after collection"))
             (loop (fx- i 1))))
         (for-each
-          (lambda (a1 a3)
-            (unless (or (car a1) (bwp-object? (car a3)))
+          (lambda (a1 a3 a4)
+            (unless (or (car a1)
+                        (and (bwp-object? (car a3))
+                             (bwp-object? (car a4))))
               (errorf #f "~s has not been bwp'd I" (car a3))))
-          ls1 ls3)
+          ls1 ls3 ls4)
         (for-each (lambda (a1) (set-car! a1 #f)) ls1)
         (collect (collect-maximum-generation))
-        (unless (andmap (lambda (a3) (bwp-object? (car a3))) ls3)
+        (unless (and (andmap (lambda (a3) (bwp-object? (car a3))) ls3)
+                     (andmap (lambda (a4) (bwp-object? (car a4))) ls4))
           (errorf #f "keys have not been bwp'd II"))
         (unless (and (equal? (hashtable-keys wht) '#())
-                     (equal? (hashtable-values ht) '#())
-                     (zero? (hashtable-size ht)))
-          (errorf #f "wht has not been cleared out"))))
+                     (equal? (hashtable-values wht) '#())
+                     (zero? (hashtable-size wht)))
+          (errorf #f "wht has not been cleared out"))
+        (unless (and (equal? (hashtable-keys eht) '#())
+                     (equal? (hashtable-values eht) '#())
+                     (zero? (hashtable-size eht)))
+          (errorf #f "eht has not been cleared out"))))
     #t)
-)
+  )
 
 (mat eqv-strange
   (begin
     (define $ht (make-eqv-hashtable))
     (define $wht (make-weak-eqv-hashtable))
+    (define $eht (make-weak-eqv-hashtable))
     (and (hashtable? $ht)
-         (hashtable? $wht)))
+         (hashtable? $wht)
+         (hashtable? $eht)))
   (eqv? (hashtable-set! $ht #f 75) (void))
   (eqv? (hashtable-ref $ht #f 80) 75)
   (eqv? (hashtable-set! $wht #f 75) (void))
   (eqv? (hashtable-ref $wht #f 80) 75)
+  (eqv? (hashtable-set! $eht #f 75) (void))
+  (eqv? (hashtable-ref $eht #f 80) 75)
   (eqv? (hashtable-set! $ht #!bwp "hello") (void))
   (equal? (hashtable-ref $ht #!bwp "goodbye") "hello")
   (eqv? (hashtable-set! $wht #!bwp "hello") (void))
+  (eqv? (hashtable-set! $eht #!bwp "hello") (void))
   (and (member (hashtable-ref $wht #!bwp "goodbye") '("hello" "goodbye")) #t)
+  (and (member (hashtable-ref $eht #!bwp "goodbye") '("hello" "goodbye")) #t)
  ; make sure that association isn't added before procedure is called
   (equal?
     (begin
@@ -2216,6 +3067,13 @@
         'doll)
       (hashtable-ref $wht 'cupie 'oops))
    '(barbie . doll))
+  (equal?
+    (begin
+      (hashtable-update! $eht 'cupie
+        (lambda (x) (hashtable-ref $eht 'cupie (cons 'barbie x)))
+        'doll)
+      (hashtable-ref $eht 'cupie 'oops))
+   '(barbie . doll))
 )
 
 (mat eqv-hashtable-stress
@@ -2293,6 +3151,44 @@
                           (f (+ i 1) (remq k keep) drop)))
                       (f (+ i 1) keep drop)))))))))
 
+  (let () ; ephemeron
+    (define pick
+      (lambda (ls)
+        (list-ref ls (random (length ls)))))
+    (define ht (make-ephemeron-eqv-hashtable 4))
+    (let ([ls (remq '|| (oblist))] [n 50000])
+      (let f ([i 0] [keep '()] [drop '()])
+        (if (= i n)
+            (and (<= (hashtable-size ht) (- n (length drop)))
+                 (begin
+                   (collect (collect-maximum-generation))
+                   (= (hashtable-size ht) (length keep)))
+                 (andmap (lambda (k)
+                           (string=?
+                             (symbol->string (hashtable-ref ht k #f))
+                             (cond
+                               [(string? k) k]
+                               [(pair? k) (car k)]
+                               [(vector? k) (vector-ref k 0)])))
+                         keep)
+                 (andmap (lambda (k) (eqv? (hashtable-ref ht k 'no) 'no))
+                         drop))
+            (let* ([x (pick ls)] [s (string-copy (symbol->string x))])
+              (let ([k (case (pick '(string pair vector))
+                         [(string) s]
+                         [(pair) (list s)]
+                         [(vector) (vector s)])])
+                (hashtable-set! ht k x)
+                (let ([keep (if (= (modulo i 5) 0) (cons k keep) keep)])
+                  (if (= (modulo i 17) 5)
+                      (let ([k (pick keep)])
+                        (hashtable-delete! ht k)
+                        (let ([drop (cons k drop)])
+                          (when (= (random 5) 3)
+                            (hashtable-delete! ht (pick drop)))
+                          (f (+ i 1) (remq k keep) drop)))
+                      (f (+ i 1) keep drop)))))))))
+
 )
 
 (mat symbol-hashtable
@@ -2318,7 +3214,8 @@
          (symbol-hashtable? h)
          (hashtable-mutable? h)
          (not (eq-hashtable? h))
-         (not (hashtable-weak? h))))
+         (not (hashtable-weak? h))
+         (not (hashtable-ephemeron? h))))
   (eq? (hashtable-hash-function h) symbol-hash)
   (eq? (hashtable-equivalence-function h) eq?)
   (equal? (hashtable-size h) 0)
@@ -2375,6 +3272,7 @@
          (symbol-hashtable? h2)
          (hashtable-mutable? h2)
          (not (hashtable-weak? h2))
+         (not (hashtable-ephemeron? h2))
          (not (eq-hashtable? h2))))
   (eq? (hashtable-hash-function h2) symbol-hash)
   (eq? (hashtable-equivalence-function h2) eq?)
@@ -2451,7 +3349,8 @@
          (symbol-hashtable? h)
          (hashtable-mutable? h)
          (not (eq-hashtable? h))
-         (not (hashtable-weak? h))))
+         (not (hashtable-weak? h))
+         (not (hashtable-ephemeron? h))))
   (eq? (hashtable-hash-function h) symbol-hash)
   (eq? (hashtable-equivalence-function h) eq?)
   (equal? (hashtable-size h) 0)
@@ -2508,6 +3407,7 @@
          (symbol-hashtable? h2)
          (hashtable-mutable? h2)
          (not (hashtable-weak? h2))
+         (not (hashtable-ephemeron? h2))
          (not (eq-hashtable? h2))))
   (eq? (hashtable-hash-function h2) symbol-hash)
   (eq? (hashtable-equivalence-function h2) eq?)
@@ -2635,6 +3535,7 @@
   (eq? (hashtable-equivalence-function $ght) equal?)
   (eq? (hashtable-mutable? $ght) #t)
   (not (hashtable-weak? $ght))
+  (not (hashtable-ephemeron? $ght))
   (eqv? (hashtable-size $ght) (vector-length $ght-keys1))
   (eqv? (#%$hashtable-veclen $ght) 8)
   (same-elements? (hashtable-keys $ght) $ght-keys1)
@@ -2689,14 +3590,16 @@
     (define $ght2 (hashtable-copy $ght))
     (and (hashtable? $ght2)
          (not (hashtable-mutable? $ght2))
-         (not (hashtable-weak? $ght2))))
+         (not (hashtable-weak? $ght2))
+         (not (hashtable-ephemeron? $ght2))))
   (eq? (hashtable-hash-function $ght) equal-hash)
   (eq? (hashtable-equivalence-function $ght) equal?)
   (begin
     (define $ght3 (hashtable-copy $ght #t))
     (and (hashtable? $ght3)
          (hashtable-mutable? $ght3)
-         (not (hashtable-weak? $ght3))))
+         (not (hashtable-weak? $ght3))
+         (not (hashtable-ephemeron? $ght3))))
   (eq? (hashtable-hash-function $ght) equal-hash)
   (eq? (hashtable-equivalence-function $ght) equal?)
   (begin
@@ -2885,9 +3788,11 @@
                         (open-file-input-port "testfile.ss")
                         fasl-read))])
         (list
+          (eq-hashtable-weak? ht2)
+          (eq-hashtable-ephemeron? ht2)
           (eq-hashtable-ref ht2 x2 #f)
           (eq-hashtable-ref ht2 'foo #f))))
-    '(because "foo"))
+    '(#f #f because "foo"))
  ; fasling out weak eq hash table
   (equal?
     (with-interrupts-disabled
@@ -2904,9 +3809,41 @@
                           (open-file-input-port "testfile.ss")
                           fasl-read))])
           (list
+            (eq-hashtable-weak? ht2)
+            (eq-hashtable-ephemeron? ht2)
             (eq-hashtable-ref ht2 x2 #f)
             (eq-hashtable-ref ht2 'foo #f)))))
-    '(because "foo"))
+    '(#t #f because "foo"))
+  (equal?
+    (let ([ht2 (cadr (call-with-port
+                       (open-file-input-port "testfile.ss")
+                       fasl-read))])
+      (collect (collect-maximum-generation))
+      (list
+        (hashtable-keys ht2)
+        (eq-hashtable-ref ht2 'foo #f)))
+    '(#(foo) "foo"))
+ ; fasling out ephemeron eq hash table
+  (equal?
+    (with-interrupts-disabled
+      (let ([x (cons 'y '!)])
+        (define ht (make-ephemeron-eq-hashtable))
+        (eq-hashtable-set! ht x 'because)
+        (eq-hashtable-set! ht 'foo "foo")
+        (let ([p (open-file-output-port "testfile.ss" (file-options replace))])
+          (fasl-write (list x ht) p)
+          (close-port p))
+        (let-values ([(x2 ht2)
+                      (apply values
+                        (call-with-port
+                          (open-file-input-port "testfile.ss")
+                          fasl-read))])
+          (list
+            (eq-hashtable-weak? ht2)
+            (eq-hashtable-ephemeron? ht2)
+            (eq-hashtable-ref ht2 x2 #f)
+            (eq-hashtable-ref ht2 'foo #f)))))
+    '(#f #t because "foo"))
   (equal?
     (let ([ht2 (cadr (call-with-port
                        (open-file-input-port "testfile.ss")
diff --git a/mats/patch-compile-0-f-t-f b/mats/patch-compile-0-f-t-f
index f456c0fe97..f4df09cb11 100644
--- a/mats/patch-compile-0-f-t-f
+++ b/mats/patch-compile-0-f-t-f
@@ -1,5 +1,5 @@
-*** errors-compile-0-f-f-f	2017-06-08 02:10:03.000000000 -0400
---- errors-compile-0-f-t-f	2017-06-08 01:38:37.000000000 -0400
+*** errors-compile-0-f-f-f	2017-07-06 20:31:25.000000000 -0600
+--- errors-compile-0-f-t-f	2017-07-06 19:50:33.000000000 -0600
 ***************
 *** 125,131 ****
   3.mo:Expected error in mat dipa-letrec: "attempt to reference undefined variable a".
@@ -92,7 +92,7 @@
   4.mo:Expected error in mat for-each: "for-each: (a . b) is not a proper list".
   4.mo:Expected error in mat for-each: "for-each: (a a a a a a ...) is circular".
 ***************
-*** 3645,3651 ****
+*** 3655,3661 ****
   misc.mo:Expected error in mat cpletrec: "foreign-procedure: no entry for "foo"".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable q".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable bar".
@@ -100,7 +100,7 @@
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable a".
---- 3645,3651 ----
+--- 3655,3661 ----
   misc.mo:Expected error in mat cpletrec: "foreign-procedure: no entry for "foo"".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable q".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable bar".
@@ -109,7 +109,7 @@
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable a".
 ***************
-*** 7095,7102 ****
+*** 7105,7112 ****
   7.mo:Expected error in mat bytes-allocated: "bytes-allocated: invalid space gnu".
   7.mo:Expected error in mat error: "a: hit me!".
   7.mo:Expected error in mat error: "f: n is 0".
@@ -118,7 +118,7 @@
   record.mo:Expected error in mat record2: "invalid value 3 for foreign type double-float".
   record.mo:Expected error in mat record2: "3 is not of type #<record type fudge>".
   record.mo:Expected error in mat record2: "make-record-type: invalid field list ((immutable double-float a) . b)".
---- 7095,7102 ----
+--- 7105,7112 ----
   7.mo:Expected error in mat bytes-allocated: "bytes-allocated: invalid space gnu".
   7.mo:Expected error in mat error: "a: hit me!".
   7.mo:Expected error in mat error: "f: n is 0".
@@ -128,7 +128,7 @@
   record.mo:Expected error in mat record2: "3 is not of type #<record type fudge>".
   record.mo:Expected error in mat record2: "make-record-type: invalid field list ((immutable double-float a) . b)".
 ***************
-*** 7104,7118 ****
+*** 7114,7128 ****
   record.mo:Expected error in mat type-descriptor: "invalid syntax (type-descriptor 3)".
   record.mo:Expected error in mat type-descriptor: "type-descriptor: unrecognized record car".
   record.mo:Expected error in mat record3: "variable set-fudge-a! is not bound".
@@ -144,7 +144,7 @@
   record.mo:Expected error in mat record9: "record-reader: invalid input #f".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
---- 7104,7118 ----
+--- 7114,7128 ----
   record.mo:Expected error in mat type-descriptor: "invalid syntax (type-descriptor 3)".
   record.mo:Expected error in mat type-descriptor: "type-descriptor: unrecognized record car".
   record.mo:Expected error in mat record3: "variable set-fudge-a! is not bound".
@@ -161,7 +161,7 @@
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
 ***************
-*** 7125,7150 ****
+*** 7135,7160 ****
   record.mo:Expected error in mat record10: "read: unresolvable cycle constructing record of type #<record type bar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
@@ -188,7 +188,7 @@
   record.mo:Expected error in mat foreign-data: "foreign-alloc: 0 is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: <int> is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: -5 is not a positive fixnum".
---- 7125,7150 ----
+--- 7135,7160 ----
   record.mo:Expected error in mat record10: "read: unresolvable cycle constructing record of type #<record type bar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
@@ -216,7 +216,7 @@
   record.mo:Expected error in mat foreign-data: "foreign-alloc: <int> is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: -5 is not a positive fixnum".
 ***************
-*** 7275,7313 ****
+*** 7285,7323 ****
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record23: "make-record-type: cannot extend sealed record type #<record type foo>".
@@ -256,7 +256,7 @@
   record.mo:Expected error in mat record?: "record?: 4 is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: a is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: #(1) is not a record type descriptor".
---- 7275,7313 ----
+--- 7285,7323 ----
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record23: "make-record-type: cannot extend sealed record type #<record type foo>".
@@ -297,7 +297,7 @@
   record.mo:Expected error in mat record?: "record?: a is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: #(1) is not a record type descriptor".
 ***************
-*** 7322,7378 ****
+*** 7332,7388 ****
   record.mo:Expected error in mat r6rs-records-procedural: "make-record-constructor-descriptor: invalid protocol flimflam".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure not-a-procedure".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure spam".
@@ -355,7 +355,7 @@
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "cannot extend define-record-type parent fratrat".
---- 7322,7378 ----
+--- 7332,7388 ----
   record.mo:Expected error in mat r6rs-records-procedural: "make-record-constructor-descriptor: invalid protocol flimflam".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure not-a-procedure".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure spam".
diff --git a/mats/patch-compile-0-t-f-f b/mats/patch-compile-0-t-f-f
index ea4110779d..84f3247ba1 100644
--- a/mats/patch-compile-0-t-f-f
+++ b/mats/patch-compile-0-t-f-f
@@ -1,5 +1,5 @@
-*** errors-compile-0-f-f-f	2017-06-08 02:10:03.000000000 -0400
---- errors-compile-0-t-f-f	2017-06-08 01:45:53.000000000 -0400
+*** errors-compile-0-f-f-f	2017-07-06 20:31:25.000000000 -0600
+--- errors-compile-0-t-f-f	2017-07-06 19:59:12.000000000 -0600
 ***************
 *** 93,99 ****
   3.mo:Expected error in mat case-lambda: "incorrect number of arguments to #<procedure foo>".
@@ -3711,8 +3711,8 @@
   bytevector.mo:Expected error in mat bytevector=?: "bytevector=?: "a" is not a bytevector".
   bytevector.mo:Expected error in mat tspl/csug-examples: "invalid endianness "spam"".
 ***************
-*** 3575,3586 ****
-  bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-truncate!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+*** 3585,3596 ****
+  bytevector.mo:Expected error in mat bytevector-compress: "bytevector-uncompress: bytevector #vu8(255 255 255 255 255 255 ...) claims invalid uncompressed size <int>".
   misc.mo:Expected error in mat compiler1: "variable i-am-not-bound is not bound".
   misc.mo:Expected error in mat compiler1: "attempt to apply non-procedure oops".
 ! misc.mo:Expected error in mat compiler1: "incorrect argument count in call (g (list))".
@@ -3724,8 +3724,8 @@
   misc.mo:Expected error in mat compiler3: "incorrect argument count in call (consumer 1 2) at line 3, char 19 of testfile.ss".
   misc.mo:Expected error in mat compiler3: "incorrect argument count in call (consumer 1 2)".
   misc.mo:Expected error in mat compiler3: "variable goto is not bound".
---- 3575,3586 ----
-  bytevector.mo:Expected error in mat bytevector->immutable-bytevector: "bytevector-truncate!: #vu8(42 42 42 42 42 42 ...) is not a mutable bytevector".
+--- 3585,3596 ----
+  bytevector.mo:Expected error in mat bytevector-compress: "bytevector-uncompress: bytevector #vu8(255 255 255 255 255 255 ...) claims invalid uncompressed size <int>".
   misc.mo:Expected error in mat compiler1: "variable i-am-not-bound is not bound".
   misc.mo:Expected error in mat compiler1: "attempt to apply non-procedure oops".
 ! misc.mo:Expected error in mat compiler1: "incorrect argument count in call (g (($top-level-value (...))))".
@@ -3738,7 +3738,7 @@
   misc.mo:Expected error in mat compiler3: "incorrect argument count in call (consumer 1 2)".
   misc.mo:Expected error in mat compiler3: "variable goto is not bound".
 ***************
-*** 3652,3672 ****
+*** 3662,3682 ****
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to assign undefined variable b".
   misc.mo:Expected error in mat compile-profile: "compile-profile: invalid mode src [must be #f, #t, source, or block]".
@@ -3760,7 +3760,7 @@
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: #t is not a string".
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: invalid dump 17".
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: invalid dump (17)".
---- 3652,3672 ----
+--- 3662,3682 ----
   misc.mo:Expected error in mat cpletrec: "attempt to reference undefined variable b".
   misc.mo:Expected error in mat cpletrec: "attempt to assign undefined variable b".
   misc.mo:Expected error in mat compile-profile: "compile-profile: invalid mode src [must be #f, #t, source, or block]".
@@ -3783,7 +3783,7 @@
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: invalid dump 17".
   misc.mo:Expected error in mat compile-profile: "profile-dump-data: invalid dump (17)".
 ***************
-*** 3699,3705 ****
+*** 3709,3715 ****
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: failed for probably-does-not-exist: no such file or directory".
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: failed for probably-does-not-exist: no such file or directory".
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: record comparison failed while comparing testfile-fatfib1.so and testfile-fatfib3.so within fasl entry 2".
@@ -3791,7 +3791,7 @@
   misc.mo:Expected error in mat cost-center: "with-cost-center: foo is not a cost center".
   misc.mo:Expected error in mat cost-center: "with-cost-center: bar is not a procedure".
   misc.mo:Expected error in mat cost-center: "cost-center-instruction-count: 5 is not a cost center".
---- 3699,3705 ----
+--- 3709,3715 ----
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: failed for probably-does-not-exist: no such file or directory".
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: failed for probably-does-not-exist: no such file or directory".
   misc.mo:Expected error in mat $fasl-file-equal?: "$fasl-file-equal?: record comparison failed while comparing testfile-fatfib1.so and testfile-fatfib3.so within fasl entry 2".
@@ -3800,7 +3800,7 @@
   misc.mo:Expected error in mat cost-center: "with-cost-center: bar is not a procedure".
   misc.mo:Expected error in mat cost-center: "cost-center-instruction-count: 5 is not a cost center".
 ***************
-*** 3753,3760 ****
+*** 3763,3770 ****
   misc.mo:Expected error in mat apropos: "apropos: 3 is not a symbol or string".
   misc.mo:Expected error in mat apropos: "apropos: (hit me) is not a symbol or string".
   misc.mo:Expected error in mat apropos: "apropos-list: b is not an environment".
@@ -3809,7 +3809,7 @@
   misc.mo:Expected error in mat apropos: "variable $apropos-unbound1 is not bound".
   misc.mo:Expected error in mat apropos: "variable $apropos-unbound2 is not bound".
   misc.mo:Expected error in mat simplify-if: "textual-port?: a is not a port".
---- 3753,3760 ----
+--- 3763,3770 ----
   misc.mo:Expected error in mat apropos: "apropos: 3 is not a symbol or string".
   misc.mo:Expected error in mat apropos: "apropos: (hit me) is not a symbol or string".
   misc.mo:Expected error in mat apropos: "apropos-list: b is not an environment".
@@ -3819,7 +3819,7 @@
   misc.mo:Expected error in mat apropos: "variable $apropos-unbound2 is not bound".
   misc.mo:Expected error in mat simplify-if: "textual-port?: a is not a port".
 ***************
-*** 3780,3788 ****
+*** 3790,3798 ****
   cp0.mo:Expected error in mat cp0-regression: "source-object-efp: #f is not a source object".
   cp0.mo:Expected error in mat cp0-regression: "source-object-sfd: #f is not a source object".
   cp0.mo:Expected error in mat cp0-regression: "condition: #f is not a condition".
@@ -3829,7 +3829,7 @@
   cp0.mo:Expected error in mat expand-output: "expand-output: #t is not a textual output port or #f".
   cp0.mo:Expected error in mat expand-output: "expand-output: #<binary output port bytevector> is not a textual output port or #f".
   cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #t is not a textual output port or #f".
---- 3780,3788 ----
+--- 3790,3798 ----
   cp0.mo:Expected error in mat cp0-regression: "source-object-efp: #f is not a source object".
   cp0.mo:Expected error in mat cp0-regression: "source-object-sfd: #f is not a source object".
   cp0.mo:Expected error in mat cp0-regression: "condition: #f is not a condition".
@@ -3840,7 +3840,7 @@
   cp0.mo:Expected error in mat expand-output: "expand-output: #<binary output port bytevector> is not a textual output port or #f".
   cp0.mo:Expected error in mat expand/optimize-output: "expand/optimize-output: #t is not a textual output port or #f".
 ***************
-*** 3846,3854 ****
+*** 3856,3864 ****
   5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 . 3) is not a proper list".
   5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 3 2 3 2 ...) is circular".
   5_6.mo:Expected error in mat fxvector->list: "fxvector->list: (a b c) is not an fxvector".
@@ -3850,7 +3850,7 @@
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
---- 3846,3854 ----
+--- 3856,3864 ----
   5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 . 3) is not a proper list".
   5_6.mo:Expected error in mat list->fxvector: "list->fxvector: (1 2 3 2 3 2 ...) is circular".
   5_6.mo:Expected error in mat fxvector->list: "fxvector->list: (a b c) is not an fxvector".
@@ -3861,7 +3861,7 @@
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
   5_6.mo:Expected error in mat vector-map: "vector-map: #() is not a procedure".
 ***************
-*** 3863,3871 ****
+*** 3873,3881 ****
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #() and #(x) differ".
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #(y) and #() differ".
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #(y) and #() differ".
@@ -3871,7 +3871,7 @@
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
---- 3863,3871 ----
+--- 3873,3881 ----
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #() and #(x) differ".
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #(y) and #() differ".
   5_6.mo:Expected error in mat vector-map: "vector-map: lengths of input vectors #(y) and #() differ".
@@ -3882,7 +3882,7 @@
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: #() is not a procedure".
 ***************
-*** 3880,3897 ****
+*** 3890,3907 ****
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #() and #(x) differ".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #(y) and #() differ".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #(y) and #() differ".
@@ -3901,7 +3901,7 @@
   5_6.mo:Expected error in mat vector-sort!: "vector-sort!: 3 is not a mutable vector".
   5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a mutable vector".
   5_6.mo:Expected error in mat vector-sort!: "vector-sort!: #(a b c) is not a procedure".
---- 3880,3897 ----
+--- 3890,3907 ----
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #() and #(x) differ".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #(y) and #() differ".
   5_6.mo:Expected error in mat vector-for-each: "vector-for-each: lengths of input vectors #(y) and #() differ".
@@ -3921,7 +3921,7 @@
   5_6.mo:Expected error in mat vector-sort!: "vector-sort!: (1 2 3) is not a mutable vector".
   5_6.mo:Expected error in mat vector-sort!: "vector-sort!: #(a b c) is not a procedure".
 ***************
-*** 3959,3980 ****
+*** 3969,3990 ****
   6.mo:Expected error in mat port-operations: "clear-output-port: not permitted on closed port #<output port testfile.ss>".
   6.mo:Expected error in mat port-operations: "current-output-port: a is not a textual output port".
   6.mo:Expected error in mat port-operations: "current-input-port: a is not a textual input port".
@@ -3944,7 +3944,7 @@
   6.mo:Expected error in mat port-operations1: "open-input-output-file: furball is not a string".
   6.mo:Expected error in mat port-operations1: "open-input-output-file: failed for /probably/not/a/good/path: no such file or directory".
   6.mo:Expected error in mat port-operations1: "open-input-output-file: invalid option compressed".
---- 3959,3980 ----
+--- 3969,3990 ----
   6.mo:Expected error in mat port-operations: "clear-output-port: not permitted on closed port #<output port testfile.ss>".
   6.mo:Expected error in mat port-operations: "current-output-port: a is not a textual output port".
   6.mo:Expected error in mat port-operations: "current-input-port: a is not a textual input port".
@@ -3968,7 +3968,7 @@
   6.mo:Expected error in mat port-operations1: "open-input-output-file: failed for /probably/not/a/good/path: no such file or directory".
   6.mo:Expected error in mat port-operations1: "open-input-output-file: invalid option compressed".
 ***************
-*** 3983,3989 ****
+*** 3993,3999 ****
   6.mo:Expected error in mat port-operations1: "truncate-file: all-the-way is not a valid length".
   6.mo:Expected error in mat port-operations1: "truncate-file: #<input port testfile.ss> is not an output port".
   6.mo:Expected error in mat port-operations1: "truncate-file: animal-crackers is not an output port".
@@ -3976,7 +3976,7 @@
   6.mo:Expected error in mat port-operations1: "truncate-file: not permitted on closed port #<input/output port testfile.ss>".
   6.mo:Expected error in mat port-operations1: "get-output-string: #<input port string> is not a string output port".
   6.mo:Expected error in mat port-operations1: "get-output-string: #<output port testfile.ss> is not a string output port".
---- 3983,3989 ----
+--- 3993,3999 ----
   6.mo:Expected error in mat port-operations1: "truncate-file: all-the-way is not a valid length".
   6.mo:Expected error in mat port-operations1: "truncate-file: #<input port testfile.ss> is not an output port".
   6.mo:Expected error in mat port-operations1: "truncate-file: animal-crackers is not an output port".
@@ -3985,7 +3985,7 @@
   6.mo:Expected error in mat port-operations1: "get-output-string: #<input port string> is not a string output port".
   6.mo:Expected error in mat port-operations1: "get-output-string: #<output port testfile.ss> is not a string output port".
 ***************
-*** 4000,4007 ****
+*** 4010,4017 ****
   6.mo:Expected error in mat string-port-file-position: "file-position: -1 is not a valid position".
   6.mo:Expected error in mat fresh-line: "fresh-line: 3 is not a textual output port".
   6.mo:Expected error in mat fresh-line: "fresh-line: #<input port string> is not a textual output port".
@@ -3994,7 +3994,7 @@
   6.mo:Expected error in mat pretty-print: "pretty-format: 3 is not a symbol".
   6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "~a~~~s" in call to format".
---- 4000,4007 ----
+--- 4010,4017 ----
   6.mo:Expected error in mat string-port-file-position: "file-position: -1 is not a valid position".
   6.mo:Expected error in mat fresh-line: "fresh-line: 3 is not a textual output port".
   6.mo:Expected error in mat fresh-line: "fresh-line: #<input port string> is not a textual output port".
@@ -4004,7 +4004,7 @@
   6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "~a~~~s" in call to format".
 ***************
-*** 6485,6516 ****
+*** 6495,6526 ****
   io.mo:Expected error in mat port-operations: "put-u8: not permitted on closed port #<binary output port testfile.ss>".
   io.mo:Expected error in mat port-operations: "put-bytevector: not permitted on closed port #<binary output port testfile.ss>".
   io.mo:Expected error in mat port-operations: "flush-output-port: not permitted on closed port #<binary output port testfile.ss>".
@@ -4037,7 +4037,7 @@
   io.mo:Expected error in mat port-operations1: "open-file-input/output-port: failed for /probably/not/a/good/path: no such file or directory".
   io.mo:Expected error in mat port-operations1: "invalid file option uncompressed".
   io.mo:Expected error in mat port-operations1: "invalid file option truncate".
---- 6485,6516 ----
+--- 6495,6526 ----
   io.mo:Expected error in mat port-operations: "put-u8: not permitted on closed port #<binary output port testfile.ss>".
   io.mo:Expected error in mat port-operations: "put-bytevector: not permitted on closed port #<binary output port testfile.ss>".
   io.mo:Expected error in mat port-operations: "flush-output-port: not permitted on closed port #<binary output port testfile.ss>".
@@ -4071,7 +4071,7 @@
   io.mo:Expected error in mat port-operations1: "invalid file option uncompressed".
   io.mo:Expected error in mat port-operations1: "invalid file option truncate".
 ***************
-*** 6521,6527 ****
+*** 6531,6537 ****
   io.mo:Expected error in mat port-operations1: "set-port-length!: all-the-way is not a valid length".
   io.mo:Expected error in mat port-operations1: "truncate-port: #<binary input port testfile.ss> is not an output port".
   io.mo:Expected error in mat port-operations1: "truncate-port: animal-crackers is not an output port".
@@ -4079,7 +4079,7 @@
   io.mo:Expected error in mat port-operations1: "truncate-port: not permitted on closed port #<binary input/output port testfile.ss>".
   io.mo:Expected error in mat port-operations3: "file-port?: "not a port" is not a port".
   io.mo:Expected error in mat port-operations3: "port-file-descriptor: oops is not a port".
---- 6521,6527 ----
+--- 6531,6537 ----
   io.mo:Expected error in mat port-operations1: "set-port-length!: all-the-way is not a valid length".
   io.mo:Expected error in mat port-operations1: "truncate-port: #<binary input port testfile.ss> is not an output port".
   io.mo:Expected error in mat port-operations1: "truncate-port: animal-crackers is not an output port".
@@ -4088,7 +4088,7 @@
   io.mo:Expected error in mat port-operations3: "file-port?: "not a port" is not a port".
   io.mo:Expected error in mat port-operations3: "port-file-descriptor: oops is not a port".
 ***************
-*** 6704,6716 ****
+*** 6714,6726 ****
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: #vu8(1 2 3) is not a valid size for #<binary output port bytevector>".
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: -1 is not a valid size for #<binary output port bytevector>".
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: 6 is not a valid size for #<binary output port bytevector>".
@@ -4102,7 +4102,7 @@
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: shoe is not a positive fixnum".
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: 0 is not a positive fixnum".
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: -15 is not a positive fixnum".
---- 6704,6716 ----
+--- 6714,6726 ----
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: #vu8(1 2 3) is not a valid size for #<binary output port bytevector>".
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: -1 is not a valid size for #<binary output port bytevector>".
   io.mo:Expected error in mat low-level-port-operations: "set-binary-port-output-size!: 6 is not a valid size for #<binary output port bytevector>".
@@ -4117,7 +4117,7 @@
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: 0 is not a positive fixnum".
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: -15 is not a positive fixnum".
 ***************
-*** 6718,6733 ****
+*** 6728,6743 ****
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: 1024.0 is not a positive fixnum".
   io.mo:Expected error in mat compression: "port-file-compressed!: #<output port string> is not a file port".
   io.mo:Expected error in mat compression: "port-file-compressed!: cannot compress input/output port #<binary input/output port testfile.ss>".
@@ -4134,7 +4134,7 @@
   io.mo:Expected error in mat custom-binary-ports: "unget-u8: cannot unget 255 on #<binary input port foo>".
   io.mo:Expected error in mat custom-binary-ports: "put-u8: #<binary input port foo> is not a binary output port".
   io.mo:Expected error in mat custom-binary-ports: "port-length: #<binary input port foo> does not support operation".
---- 6718,6733 ----
+--- 6728,6743 ----
   io.mo:Expected error in mat custom-port-buffer-size: "custom-port-buffer-size: 1024.0 is not a positive fixnum".
   io.mo:Expected error in mat compression: "port-file-compressed!: #<output port string> is not a file port".
   io.mo:Expected error in mat compression: "port-file-compressed!: cannot compress input/output port #<binary input/output port testfile.ss>".
@@ -4152,7 +4152,7 @@
   io.mo:Expected error in mat custom-binary-ports: "put-u8: #<binary input port foo> is not a binary output port".
   io.mo:Expected error in mat custom-binary-ports: "port-length: #<binary input port foo> does not support operation".
 ***************
-*** 6799,6814 ****
+*** 6809,6824 ****
   io.mo:Expected error in mat current-ports: "console-output-port: #<input port string> is not a textual output port".
   io.mo:Expected error in mat current-ports: "console-error-port: #<input port string> is not a textual output port".
   io.mo:Expected error in mat current-transcoder: "current-transcoder: #<output port string> is not a transcoder".
@@ -4169,7 +4169,7 @@
   io.mo:Expected error in mat utf-16-codec: "utf-16-codec: invalid endianness #f".
   io.mo:Expected error in mat to-fold-or-not-to-fold: "get-datum: invalid character name #\newLine at char 0 of #<input port string>".
   io.mo:Expected error in mat to-fold-or-not-to-fold: "get-datum: invalid character name #\newLine at char 15 of #<input port string>".
---- 6799,6814 ----
+--- 6809,6824 ----
   io.mo:Expected error in mat current-ports: "console-output-port: #<input port string> is not a textual output port".
   io.mo:Expected error in mat current-ports: "console-error-port: #<input port string> is not a textual output port".
   io.mo:Expected error in mat current-transcoder: "current-transcoder: #<output port string> is not a transcoder".
@@ -4187,7 +4187,7 @@
   io.mo:Expected error in mat to-fold-or-not-to-fold: "get-datum: invalid character name #\newLine at char 0 of #<input port string>".
   io.mo:Expected error in mat to-fold-or-not-to-fold: "get-datum: invalid character name #\newLine at char 15 of #<input port string>".
 ***************
-*** 6979,6985 ****
+*** 6989,6995 ****
   7.mo:Expected error in mat eval-when: "invalid syntax visit-x".
   7.mo:Expected error in mat eval-when: "invalid syntax revisit-x".
   7.mo:Expected error in mat compile-whole-program: "compile-whole-program: failed for nosuchfile.wpo: no such file or directory".
@@ -4195,7 +4195,7 @@
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: library (testfile-wpo-a4) not found
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: library (testfile-wpo-c4) not found
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: attempt to invoke library (testfile-wpo-c5) while it is still being loaded
---- 6979,6985 ----
+--- 6989,6995 ----
   7.mo:Expected error in mat eval-when: "invalid syntax visit-x".
   7.mo:Expected error in mat eval-when: "invalid syntax revisit-x".
   7.mo:Expected error in mat compile-whole-program: "compile-whole-program: failed for nosuchfile.wpo: no such file or directory".
@@ -4204,7 +4204,7 @@
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: library (testfile-wpo-c4) not found
   7.mo:Expected error in mat compile-whole-program: "separate-eval: Exception: attempt to invoke library (testfile-wpo-c5) while it is still being loaded
 ***************
-*** 6993,7019 ****
+*** 7003,7029 ****
   7.mo:Expected error in mat compile-whole-library: "separate-eval: Exception: library (testfile-cwl-c6) not found
   7.mo:Expected error in mat compile-whole-library: "separate-compile: Exception in compile-whole-library: encountered visit-only run-time library (testfile-cwl-a9) while processing file "testfile-cwl-a9.wpo"
   7.mo:Expected error in mat top-level-value-functions: "top-level-bound?: "hello" is not a symbol".
@@ -4232,7 +4232,7 @@
   7.mo:Expected error in mat top-level-value-functions: "define-top-level-value: hello is not an environment".
   7.mo:Expected error in mat top-level-value-functions: "define-top-level-value: #<environment *scheme*> is not a symbol".
   7.mo:Expected error in mat top-level-value-functions: "variable i-am-not-bound-i-hope is not bound".
---- 6993,7019 ----
+--- 7003,7029 ----
   7.mo:Expected error in mat compile-whole-library: "separate-eval: Exception: library (testfile-cwl-c6) not found
   7.mo:Expected error in mat compile-whole-library: "separate-compile: Exception in compile-whole-library: encountered visit-only run-time library (testfile-cwl-a9) while processing file "testfile-cwl-a9.wpo"
   7.mo:Expected error in mat top-level-value-functions: "top-level-bound?: "hello" is not a symbol".
@@ -4261,7 +4261,7 @@
   7.mo:Expected error in mat top-level-value-functions: "define-top-level-value: #<environment *scheme*> is not a symbol".
   7.mo:Expected error in mat top-level-value-functions: "variable i-am-not-bound-i-hope is not bound".
 ***************
-*** 7410,7500 ****
+*** 7420,7513 ****
   hash.mo:Expected error in mat old-hash-table: "hash-table-for-each: ((a . b)) is not an eq hashtable".
   hash.mo:Expected error in mat old-hash-table: "incorrect number of arguments to #<procedure>".
   hash.mo:Expected error in mat old-hash-table: "incorrect number of arguments to #<procedure>".
@@ -4351,9 +4351,12 @@
 ! hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-weak?)".
 ! hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-weak? $ht 3)".
   hash.mo:Expected error in mat hashtable-arguments: "hashtable-weak?: (hash . table) is not a hashtable".
+! hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-ephemeron?)".
+! hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-ephemeron? $ht 3)".
+  hash.mo:Expected error in mat hashtable-arguments: "hashtable-ephemeron?: (hash . table) is not a hashtable".
   hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value "oops" for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value 3.5 for any".
---- 7410,7500 ----
+--- 7420,7513 ----
   hash.mo:Expected error in mat old-hash-table: "hash-table-for-each: ((a . b)) is not an eq hashtable".
   hash.mo:Expected error in mat old-hash-table: "incorrect number of arguments to #<procedure>".
   hash.mo:Expected error in mat old-hash-table: "incorrect number of arguments to #<procedure>".
@@ -4443,10 +4446,13 @@
 ! hash.mo:Expected error in mat hashtable-arguments: "incorrect number of arguments to #<procedure hashtable-weak?>".
 ! hash.mo:Expected error in mat hashtable-arguments: "incorrect number of arguments to #<procedure hashtable-weak?>".
   hash.mo:Expected error in mat hashtable-arguments: "hashtable-weak?: (hash . table) is not a hashtable".
+! hash.mo:Expected error in mat hashtable-arguments: "incorrect number of arguments to #<procedure hashtable-ephemeron?>".
+! hash.mo:Expected error in mat hashtable-arguments: "incorrect number of arguments to #<procedure hashtable-ephemeron?>".
+  hash.mo:Expected error in mat hashtable-arguments: "hashtable-ephemeron?: (hash . table) is not a hashtable".
   hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value "oops" for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value 3.5 for any".
 ***************
-*** 7514,7609 ****
+*** 7527,7633 ****
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value "oops" for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value 3.5 for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value 1+2i for any".
@@ -4454,6 +4460,10 @@
   hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument -1".
   hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument #t".
   hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument #f".
+! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (make-ephemeron-eq-hashtable 3 #t)".
+  hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument -1".
+  hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument #t".
+  hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument #f".
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref)".
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref $wht)".
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref $wht (quote a))".
@@ -4489,6 +4499,9 @@
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-weak?)".
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-weak? $ht 3)".
   hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-weak?: (hash . table) is not an eq hashtable".
+! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ephemeron?)".
+! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ephemeron? $ht 3)".
+  hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-ephemeron?: (hash . table) is not an eq hashtable".
 ! hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref)".
 ! hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref $symht)".
 ! hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref $symht (quote a))".
@@ -4543,7 +4556,11 @@
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument -1".
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #t".
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #f".
---- 7514,7609 ----
+! hash.mo:Expected error in mat eqv-hashtable-arguments: "incorrect argument count in call (make-ephemeron-eqv-hashtable 3 #t)".
+  hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument -1".
+  hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument #t".
+  hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument #f".
+--- 7527,7633 ----
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value "oops" for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value 3.5 for any".
   hash.mo:Expected error in mat hash-return-value: "hashtable-delete!: invalid hash-function #<procedure> return value 1+2i for any".
@@ -4551,6 +4568,10 @@
   hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument -1".
   hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument #t".
   hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument #f".
+! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect number of arguments to #<procedure make-ephemeron-eq-hashtable>".
+  hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument -1".
+  hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument #t".
+  hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument #f".
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect number of arguments to #<procedure eq-hashtable-ref>".
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect number of arguments to #<procedure eq-hashtable-ref>".
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect number of arguments to #<procedure eq-hashtable-ref>".
@@ -4586,6 +4607,9 @@
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect number of arguments to #<procedure eq-hashtable-weak?>".
 ! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect number of arguments to #<procedure eq-hashtable-weak?>".
   hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-weak?: (hash . table) is not an eq hashtable".
+! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect number of arguments to #<procedure eq-hashtable-ephemeron?>".
+! hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect number of arguments to #<procedure eq-hashtable-ephemeron?>".
+  hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-ephemeron?: (hash . table) is not an eq hashtable".
 ! hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect number of arguments to #<procedure symbol-hashtable-ref>".
 ! hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect number of arguments to #<procedure symbol-hashtable-ref>".
 ! hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect number of arguments to #<procedure symbol-hashtable-ref>".
@@ -4640,8 +4664,12 @@
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument -1".
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #t".
   hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #f".
+! hash.mo:Expected error in mat eqv-hashtable-arguments: "incorrect number of arguments to #<procedure make-ephemeron-eqv-hashtable>".
+  hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument -1".
+  hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument #t".
+  hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument #f".
 ***************
-*** 7611,7626 ****
+*** 7635,7650 ****
   hash.mo:Expected error in mat generic-hashtable: "hashtable-delete!: #<hashtable> is not mutable".
   hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
   hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
@@ -4658,7 +4686,7 @@
   hash.mo:Expected error in mat hash-functions: "string-ci-hash: hello is not a string".
   hash.mo:Expected error in mat fasl-other-hashtable: "fasl-write: invalid fasl object #<eqv hashtable>".
   hash.mo:Expected error in mat fasl-other-hashtable: "fasl-write: invalid fasl object #<hashtable>".
---- 7611,7626 ----
+--- 7635,7650 ----
   hash.mo:Expected error in mat generic-hashtable: "hashtable-delete!: #<hashtable> is not mutable".
   hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
   hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
@@ -4676,7 +4704,7 @@
   hash.mo:Expected error in mat fasl-other-hashtable: "fasl-write: invalid fasl object #<eqv hashtable>".
   hash.mo:Expected error in mat fasl-other-hashtable: "fasl-write: invalid fasl object #<hashtable>".
 ***************
-*** 7736,7743 ****
+*** 7760,7767 ****
   8.mo:Expected error in mat with-syntax: "invalid syntax a".
   8.mo:Expected error in mat with-syntax: "duplicate pattern variable x in (x x)".
   8.mo:Expected error in mat with-syntax: "duplicate pattern variable x in (x x)".
@@ -4685,7 +4713,7 @@
   8.mo:Expected error in mat generate-temporaries: "generate-temporaries: improper list structure (a b . c)".
   8.mo:Expected error in mat generate-temporaries: "generate-temporaries: cyclic list structure (a b c b c b ...)".
   8.mo:Expected error in mat syntax->list: "syntax->list: invalid argument #<syntax a>".
---- 7736,7743 ----
+--- 7760,7767 ----
   8.mo:Expected error in mat with-syntax: "invalid syntax a".
   8.mo:Expected error in mat with-syntax: "duplicate pattern variable x in (x x)".
   8.mo:Expected error in mat with-syntax: "duplicate pattern variable x in (x x)".
@@ -4695,7 +4723,7 @@
   8.mo:Expected error in mat generate-temporaries: "generate-temporaries: cyclic list structure (a b c b c b ...)".
   8.mo:Expected error in mat syntax->list: "syntax->list: invalid argument #<syntax a>".
 ***************
-*** 8325,8340 ****
+*** 8349,8364 ****
   8.mo:Expected error in mat rnrs-eval: "attempt to assign unbound identifier foo".
   8.mo:Expected error in mat rnrs-eval: "invalid definition in immutable environment (define cons (quote #<procedure vector>))".
   8.mo:Expected error in mat top-level-syntax-functions: "top-level-syntax: "hello" is not a symbol".
@@ -4712,7 +4740,7 @@
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: hello is not an environment".
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: #<environment *scheme*> is not a symbol".
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: cannot modify immutable environment #<environment *scheme*>".
---- 8325,8340 ----
+--- 8349,8364 ----
   8.mo:Expected error in mat rnrs-eval: "attempt to assign unbound identifier foo".
   8.mo:Expected error in mat rnrs-eval: "invalid definition in immutable environment (define cons (quote #<procedure vector>))".
   8.mo:Expected error in mat top-level-syntax-functions: "top-level-syntax: "hello" is not a symbol".
@@ -4730,7 +4758,7 @@
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: #<environment *scheme*> is not a symbol".
   8.mo:Expected error in mat top-level-syntax-functions: "define-top-level-syntax: cannot modify immutable environment #<environment *scheme*>".
 ***************
-*** 8413,8435 ****
+*** 8437,8459 ****
   fx.mo:Expected error in mat fx=?: "fx=?: (a) is not a fixnum".
   fx.mo:Expected error in mat fx=?: "fx=?: <int> is not a fixnum".
   fx.mo:Expected error in mat fx=?: "fx=?: <-int> is not a fixnum".
@@ -4754,7 +4782,7 @@
   fx.mo:Expected error in mat $fxu<: "incorrect number of arguments to #<procedure $fxu<>".
   fx.mo:Expected error in mat $fxu<: "incorrect number of arguments to #<procedure $fxu<>".
   fx.mo:Expected error in mat $fxu<: "$fxu<: <-int> is not a fixnum".
---- 8413,8435 ----
+--- 8437,8459 ----
   fx.mo:Expected error in mat fx=?: "fx=?: (a) is not a fixnum".
   fx.mo:Expected error in mat fx=?: "fx=?: <int> is not a fixnum".
   fx.mo:Expected error in mat fx=?: "fx=?: <-int> is not a fixnum".
@@ -4779,7 +4807,7 @@
   fx.mo:Expected error in mat $fxu<: "incorrect number of arguments to #<procedure $fxu<>".
   fx.mo:Expected error in mat $fxu<: "$fxu<: <-int> is not a fixnum".
 ***************
-*** 8461,8473 ****
+*** 8485,8497 ****
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -4793,7 +4821,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
---- 8461,8473 ----
+--- 8485,8497 ----
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -4808,7 +4836,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
 ***************
-*** 8517,8529 ****
+*** 8541,8553 ****
   fx.mo:Expected error in mat fx1+: "fx1+: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx1+: "fx1+: <int> is not a fixnum".
   fx.mo:Expected error in mat fx1+: "fx1+: a is not a fixnum".
@@ -4822,7 +4850,7 @@
   fx.mo:Expected error in mat fxmax: "fxmax: a is not a fixnum".
   fx.mo:Expected error in mat fxmax: "fxmax: <int> is not a fixnum".
   fx.mo:Expected error in mat fxmax: "fxmax: <-int> is not a fixnum".
---- 8517,8529 ----
+--- 8541,8553 ----
   fx.mo:Expected error in mat fx1+: "fx1+: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx1+: "fx1+: <int> is not a fixnum".
   fx.mo:Expected error in mat fx1+: "fx1+: a is not a fixnum".
@@ -4837,7 +4865,7 @@
   fx.mo:Expected error in mat fxmax: "fxmax: <int> is not a fixnum".
   fx.mo:Expected error in mat fxmax: "fxmax: <-int> is not a fixnum".
 ***************
-*** 8621,8630 ****
+*** 8645,8654 ****
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments <int> and 10".
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments -4097 and <int>".
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments <-int> and 1".
@@ -4848,7 +4876,7 @@
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 35.0 is not a fixnum".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 5.0 is not a valid start index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 8.0 is not a valid end index".
---- 8621,8630 ----
+--- 8645,8654 ----
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments <int> and 10".
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments -4097 and <int>".
   fx.mo:Expected error in mat fxarithmetic-shift: "fxarithmetic-shift: fixnum overflow with arguments <-int> and 1".
@@ -4860,7 +4888,7 @@
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 5.0 is not a valid start index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: 8.0 is not a valid end index".
 ***************
-*** 8638,8671 ****
+*** 8662,8695 ****
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid end index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid start index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid end index".
@@ -4895,7 +4923,7 @@
   fx.mo:Expected error in mat fxif: "fxif: a is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: 3.4 is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: (a) is not a fixnum".
---- 8638,8671 ----
+--- 8662,8695 ----
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid end index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid start index".
   fx.mo:Expected error in mat fxbit-field: "fxbit-field: <int> is not a valid end index".
@@ -4931,7 +4959,7 @@
   fx.mo:Expected error in mat fxif: "fxif: 3.4 is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: (a) is not a fixnum".
 ***************
-*** 8675,8718 ****
+*** 8699,8742 ****
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
@@ -4976,7 +5004,7 @@
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: 3.4 is not a fixnum".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: "3" is not a fixnum".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: <int> is not a fixnum".
---- 8675,8718 ----
+--- 8699,8742 ----
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
   fx.mo:Expected error in mat fxif: "fxif: <-int> is not a fixnum".
@@ -5022,7 +5050,7 @@
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: "3" is not a fixnum".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: <int> is not a fixnum".
 ***************
-*** 8721,8731 ****
+*** 8745,8755 ****
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index -1".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index <int>".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index <int>".
@@ -5034,7 +5062,7 @@
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: "3" is not a fixnum".
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: 3.4 is not a valid start index".
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: 3/4 is not a valid end index".
---- 8721,8731 ----
+--- 8745,8755 ----
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index -1".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index <int>".
   fx.mo:Expected error in mat fxcopy-bit: "fxcopy-bit: invalid bit index <int>".
@@ -5047,7 +5075,7 @@
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: 3.4 is not a valid start index".
   fx.mo:Expected error in mat fxcopy-bit-field: "fxcopy-bit-field: 3/4 is not a valid end index".
 ***************
-*** 8785,8794 ****
+*** 8809,8818 ****
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: (a) is not a fixnum".
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: undefined for 0".
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: undefined for 0".
@@ -5058,7 +5086,7 @@
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 1.0 is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 3.0 is not a fixnum".
---- 8785,8794 ----
+--- 8809,8818 ----
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: (a) is not a fixnum".
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: undefined for 0".
   fx.mo:Expected error in mat fxdiv0-and-mod0: "fxmod0: undefined for 0".
@@ -5070,7 +5098,7 @@
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: 3.0 is not a fixnum".
 ***************
-*** 8804,8813 ****
+*** 8828,8837 ****
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
@@ -5081,7 +5109,7 @@
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 1.0 is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 3.0 is not a fixnum".
---- 8804,8813 ----
+--- 8828,8837 ----
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx+/carry: "fx+/carry: <-int> is not a fixnum".
@@ -5093,7 +5121,7 @@
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: 3.0 is not a fixnum".
 ***************
-*** 8823,8832 ****
+*** 8847,8856 ****
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
@@ -5104,7 +5132,7 @@
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 1.0 is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 3.0 is not a fixnum".
---- 8823,8832 ----
+--- 8847,8856 ----
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx-/carry: "fx-/carry: <-int> is not a fixnum".
@@ -5116,7 +5144,7 @@
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 2.0 is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: 3.0 is not a fixnum".
 ***************
-*** 8842,8852 ****
+*** 8866,8876 ****
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
@@ -5128,7 +5156,7 @@
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: a is not a fixnum".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid start index 0.0".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index 2.0".
---- 8842,8852 ----
+--- 8866,8876 ----
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
   fx.mo:Expected error in mat fx*/carry: "fx*/carry: <-int> is not a fixnum".
@@ -5141,7 +5169,7 @@
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid start index 0.0".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index 2.0".
 ***************
-*** 8869,8878 ****
+*** 8893,8902 ****
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: count 1 is greater than difference between end index 5 and start index 5".
@@ -5152,7 +5180,7 @@
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: a is not a fixnum".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid start index 0.0".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index 2.0".
---- 8869,8878 ----
+--- 8893,8902 ----
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxrotate-bit-field: "fxrotate-bit-field: count 1 is greater than difference between end index 5 and start index 5".
@@ -5164,7 +5192,7 @@
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid start index 0.0".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index 2.0".
 ***************
-*** 8888,8905 ****
+*** 8912,8929 ****
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index <-int>".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: start index 7 is greater than end index 5".
@@ -5183,7 +5211,7 @@
   fl.mo:Expected error in mat fl=: "fl=: (a) is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: a is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: a is not a flonum".
---- 8888,8905 ----
+--- 8912,8929 ----
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index <int>".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: invalid end index <-int>".
   fx.mo:Expected error in mat fxreverse-bit-field: "fxreverse-bit-field: start index 7 is greater than end index 5".
@@ -5203,7 +5231,7 @@
   fl.mo:Expected error in mat fl=: "fl=: a is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: a is not a flonum".
 ***************
-*** 8907,8913 ****
+*** 8931,8937 ****
   fl.mo:Expected error in mat fl=: "fl=: 3 is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: 7/2 is not a flonum".
@@ -5211,7 +5239,7 @@
   fl.mo:Expected error in mat fl<: "fl<: (a) is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: a is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: a is not a flonum".
---- 8907,8913 ----
+--- 8931,8937 ----
   fl.mo:Expected error in mat fl=: "fl=: 3 is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl=: "fl=: 7/2 is not a flonum".
@@ -5220,7 +5248,7 @@
   fl.mo:Expected error in mat fl<: "fl<: a is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: a is not a flonum".
 ***************
-*** 8915,8921 ****
+*** 8939,8945 ****
   fl.mo:Expected error in mat fl<: "fl<: 3 is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: 7/2 is not a flonum".
@@ -5228,7 +5256,7 @@
   fl.mo:Expected error in mat fl>: "fl>: (a) is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: a is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: a is not a flonum".
---- 8915,8921 ----
+--- 8939,8945 ----
   fl.mo:Expected error in mat fl<: "fl<: 3 is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl<: "fl<: 7/2 is not a flonum".
@@ -5237,7 +5265,7 @@
   fl.mo:Expected error in mat fl>: "fl>: a is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: a is not a flonum".
 ***************
-*** 8923,8929 ****
+*** 8947,8953 ****
   fl.mo:Expected error in mat fl>: "fl>: 3 is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: 7/2 is not a flonum".
@@ -5245,7 +5273,7 @@
   fl.mo:Expected error in mat fl<=: "fl<=: (a) is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: a is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: a is not a flonum".
---- 8923,8929 ----
+--- 8947,8953 ----
   fl.mo:Expected error in mat fl>: "fl>: 3 is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl>: "fl>: 7/2 is not a flonum".
@@ -5254,7 +5282,7 @@
   fl.mo:Expected error in mat fl<=: "fl<=: a is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: a is not a flonum".
 ***************
-*** 8931,8937 ****
+*** 8955,8961 ****
   fl.mo:Expected error in mat fl<=: "fl<=: 3 is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: 7/2 is not a flonum".
@@ -5262,7 +5290,7 @@
   fl.mo:Expected error in mat fl>=: "fl>=: (a) is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: a is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: a is not a flonum".
---- 8931,8937 ----
+--- 8955,8961 ----
   fl.mo:Expected error in mat fl<=: "fl<=: 3 is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl<=: "fl<=: 7/2 is not a flonum".
@@ -5271,7 +5299,7 @@
   fl.mo:Expected error in mat fl>=: "fl>=: a is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: a is not a flonum".
 ***************
-*** 8939,8978 ****
+*** 8963,9002 ****
   fl.mo:Expected error in mat fl>=: "fl>=: 3 is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: 7/2 is not a flonum".
@@ -5312,7 +5340,7 @@
   fl.mo:Expected error in mat fl>=?: "fl>=?: a is not a flonum".
   fl.mo:Expected error in mat fl>=?: "fl>=?: a is not a flonum".
   fl.mo:Expected error in mat fl>=?: "fl>=?: 3 is not a flonum".
---- 8939,8978 ----
+--- 8963,9002 ----
   fl.mo:Expected error in mat fl>=: "fl>=: 3 is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: 7/2 is not a flonum".
   fl.mo:Expected error in mat fl>=: "fl>=: 7/2 is not a flonum".
@@ -5354,7 +5382,7 @@
   fl.mo:Expected error in mat fl>=?: "fl>=?: a is not a flonum".
   fl.mo:Expected error in mat fl>=?: "fl>=?: 3 is not a flonum".
 ***************
-*** 8982,8988 ****
+*** 9006,9012 ****
   fl.mo:Expected error in mat fl+: "fl+: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl+: "fl+: 1 is not a flonum".
   fl.mo:Expected error in mat fl+: "fl+: 2/3 is not a flonum".
@@ -5362,7 +5390,7 @@
   fl.mo:Expected error in mat fl-: "fl-: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl-: "fl-: 1 is not a flonum".
   fl.mo:Expected error in mat fl-: "fl-: a is not a flonum".
---- 8982,8988 ----
+--- 9006,9012 ----
   fl.mo:Expected error in mat fl+: "fl+: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl+: "fl+: 1 is not a flonum".
   fl.mo:Expected error in mat fl+: "fl+: 2/3 is not a flonum".
@@ -5371,7 +5399,7 @@
   fl.mo:Expected error in mat fl-: "fl-: 1 is not a flonum".
   fl.mo:Expected error in mat fl-: "fl-: a is not a flonum".
 ***************
-*** 8992,9074 ****
+*** 9016,9098 ****
   fl.mo:Expected error in mat fl*: "fl*: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl*: "fl*: 1 is not a flonum".
   fl.mo:Expected error in mat fl*: "fl*: 2/3 is not a flonum".
@@ -5455,7 +5483,7 @@
   fl.mo:Expected error in mat flround: "flround: a is not a flonum".
   fl.mo:Expected error in mat flround: "flround: 2.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flround: "flround: 2+1i is not a flonum".
---- 8992,9074 ----
+--- 9016,9098 ----
   fl.mo:Expected error in mat fl*: "fl*: (a . b) is not a flonum".
   fl.mo:Expected error in mat fl*: "fl*: 1 is not a flonum".
   fl.mo:Expected error in mat fl*: "fl*: 2/3 is not a flonum".
@@ -5540,7 +5568,7 @@
   fl.mo:Expected error in mat flround: "flround: 2.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flround: "flround: 2+1i is not a flonum".
 ***************
-*** 9088,9136 ****
+*** 9112,9160 ****
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: 3 is not a flonum".
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: 3/4 is not a flonum".
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: hi is not a flonum".
@@ -5590,7 +5618,7 @@
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
---- 9088,9136 ----
+--- 9112,9160 ----
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: 3 is not a flonum".
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: 3/4 is not a flonum".
   fl.mo:Expected error in mat flinfinite?: "flinfinite?: hi is not a flonum".
@@ -5641,7 +5669,7 @@
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
 ***************
-*** 9138,9144 ****
+*** 9162,9168 ****
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: 0.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: 0+1i is not a flonum".
@@ -5649,7 +5677,7 @@
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 3 is not a flonum".
---- 9138,9144 ----
+--- 9162,9168 ----
   fl.mo:Expected error in mat flmin: "flmin: a is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: 0.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flmin: "flmin: 0+1i is not a flonum".
@@ -5658,7 +5686,7 @@
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 3 is not a flonum".
 ***************
-*** 9146,9159 ****
+*** 9170,9183 ****
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 0.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 0+1i is not a flonum".
@@ -5673,7 +5701,7 @@
   fl.mo:Expected error in mat fldenominator: "fldenominator: a is not a flonum".
   fl.mo:Expected error in mat fldenominator: "fldenominator: 3 is not a flonum".
   fl.mo:Expected error in mat fldenominator: "fldenominator: 0+1i is not a flonum".
---- 9146,9159 ----
+--- 9170,9183 ----
   fl.mo:Expected error in mat flmax: "flmax: a is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 0.0+1.0i is not a flonum".
   fl.mo:Expected error in mat flmax: "flmax: 0+1i is not a flonum".
@@ -5689,7 +5717,7 @@
   fl.mo:Expected error in mat fldenominator: "fldenominator: 3 is not a flonum".
   fl.mo:Expected error in mat fldenominator: "fldenominator: 0+1i is not a flonum".
 ***************
-*** 9199,9205 ****
+*** 9223,9229 ****
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
@@ -5697,7 +5725,7 @@
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
---- 9199,9205 ----
+--- 9223,9229 ----
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
@@ -5706,7 +5734,7 @@
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
   cfl.mo:Expected error in mat cfl-: "cfl-: a is not a cflonum".
 ***************
-*** 9209,9222 ****
+*** 9233,9246 ****
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
@@ -5721,7 +5749,7 @@
   foreign.mo:Expected error in mat load-shared-object: "load-shared-object: invalid path 3".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: no entry for "i do not exist"".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: no entry for "i do not exist"".
---- 9209,9222 ----
+--- 9233,9246 ----
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
   cfl.mo:Expected error in mat cfl/: "cfl/: a is not a cflonum".
@@ -5737,7 +5765,7 @@
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: no entry for "i do not exist"".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: no entry for "i do not exist"".
 ***************
-*** 9251,9258 ****
+*** 9275,9282 ****
   foreign.mo:Expected error in mat foreign-procedure: "id: invalid foreign-procedure argument foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle abcde".
   foreign.mo:Expected error in mat foreign-procedure: "float_id: invalid foreign-procedure argument 0".
@@ -5746,7 +5774,7 @@
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier i-am-not-a-type".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier 1".
   foreign.mo:Expected error in mat foreign-bytevectors: "u8*->u8*: invalid foreign-procedure argument "hello"".
---- 9251,9258 ----
+--- 9275,9282 ----
   foreign.mo:Expected error in mat foreign-procedure: "id: invalid foreign-procedure argument foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle abcde".
   foreign.mo:Expected error in mat foreign-procedure: "float_id: invalid foreign-procedure argument 0".
@@ -5756,7 +5784,7 @@
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier 1".
   foreign.mo:Expected error in mat foreign-bytevectors: "u8*->u8*: invalid foreign-procedure argument "hello"".
 ***************
-*** 9736,9748 ****
+*** 9760,9772 ****
   unix.mo:Expected error in mat file-operations: "file-access-time: failed for "testlink": no such file or directory".
   unix.mo:Expected error in mat file-operations: "file-change-time: failed for "testlink": no such file or directory".
   unix.mo:Expected error in mat file-operations: "file-modification-time: failed for "testlink": no such file or directory".
@@ -5770,7 +5798,7 @@
   windows.mo:Expected error in mat registry: "get-registry: pooh is not a string".
   windows.mo:Expected error in mat registry: "put-registry!: 3 is not a string".
   windows.mo:Expected error in mat registry: "put-registry!: 3 is not a string".
---- 9736,9748 ----
+--- 9760,9772 ----
   unix.mo:Expected error in mat file-operations: "file-access-time: failed for "testlink": no such file or directory".
   unix.mo:Expected error in mat file-operations: "file-change-time: failed for "testlink": no such file or directory".
   unix.mo:Expected error in mat file-operations: "file-modification-time: failed for "testlink": no such file or directory".
@@ -5785,7 +5813,7 @@
   windows.mo:Expected error in mat registry: "put-registry!: 3 is not a string".
   windows.mo:Expected error in mat registry: "put-registry!: 3 is not a string".
 ***************
-*** 9770,9841 ****
+*** 9794,9865 ****
   ieee.mo:Expected error in mat flonum->fixnum: "flonum->fixnum: result for -inf.0 would be outside of fixnum range".
   ieee.mo:Expected error in mat flonum->fixnum: "flonum->fixnum: result for +nan.0 would be outside of fixnum range".
   ieee.mo:Expected error in mat fllp: "fllp: 3 is not a flonum".
@@ -5858,7 +5886,7 @@
   date.mo:Expected error in mat time: "time>=?: 3 is not a time record".
   date.mo:Expected error in mat time: "time>=?: #<procedure car> is not a time record".
   date.mo:Expected error in mat time: "time>=?: types of <time> and <time> differ".
---- 9770,9841 ----
+--- 9794,9865 ----
   ieee.mo:Expected error in mat flonum->fixnum: "flonum->fixnum: result for -inf.0 would be outside of fixnum range".
   ieee.mo:Expected error in mat flonum->fixnum: "flonum->fixnum: result for +nan.0 would be outside of fixnum range".
   ieee.mo:Expected error in mat fllp: "fllp: 3 is not a flonum".
@@ -5932,7 +5960,7 @@
   date.mo:Expected error in mat time: "time>=?: #<procedure car> is not a time record".
   date.mo:Expected error in mat time: "time>=?: types of <time> and <time> differ".
 ***************
-*** 9843,9856 ****
+*** 9867,9880 ****
   date.mo:Expected error in mat time: "add-duration: <time> does not have type time-duration".
   date.mo:Expected error in mat time: "subtract-duration: <time> does not have type time-duration".
   date.mo:Expected error in mat time: "copy-time: <date> is not a time record".
@@ -5947,7 +5975,7 @@
   date.mo:Expected error in mat date: "make-date: invalid nanosecond -1".
   date.mo:Expected error in mat date: "make-date: invalid nanosecond <int>".
   date.mo:Expected error in mat date: "make-date: invalid nanosecond zero".
---- 9843,9856 ----
+--- 9867,9880 ----
   date.mo:Expected error in mat time: "add-duration: <time> does not have type time-duration".
   date.mo:Expected error in mat time: "subtract-duration: <time> does not have type time-duration".
   date.mo:Expected error in mat time: "copy-time: <date> is not a time record".
@@ -5963,7 +5991,7 @@
   date.mo:Expected error in mat date: "make-date: invalid nanosecond <int>".
   date.mo:Expected error in mat date: "make-date: invalid nanosecond zero".
 ***************
-*** 9876,9936 ****
+*** 9900,9960 ****
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset 90000".
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset est".
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset "est"".
@@ -6025,7 +6053,7 @@
   date.mo:Expected error in mat date: "current-date: invalid time-zone offset -90000".
   date.mo:Expected error in mat date: "current-date: invalid time-zone offset 90000".
   date.mo:Expected error in mat conversions/sleep: "date->time-utc: <time> is not a date record".
---- 9876,9936 ----
+--- 9900,9960 ----
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset 90000".
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset est".
   date.mo:Expected error in mat date: "make-date: invalid time-zone offset "est"".
diff --git a/mats/patch-interpret-0-f-f-f b/mats/patch-interpret-0-f-f-f
index ea0d40a16a..0553170f8e 100644
--- a/mats/patch-interpret-0-f-f-f
+++ b/mats/patch-interpret-0-f-f-f
@@ -1,5 +1,5 @@
-*** errors-compile-0-f-f-f	2017-06-08 02:10:03.000000000 -0400
---- errors-interpret-0-f-f-f	2017-06-08 01:53:14.000000000 -0400
+*** errors-compile-0-f-f-f	2017-07-06 20:31:25.000000000 -0600
+--- errors-interpret-0-f-f-f	2017-07-06 20:08:28.000000000 -0600
 ***************
 *** 1,7 ****
   primvars.mo:Expected error in mat make-parameter: "make-parameter: 2 is not a procedure".
@@ -196,7 +196,7 @@
   3.mo:Expected error in mat mrvs: "returned two values to single value return context".
   3.mo:Expected error in mat mrvs: "cdr: a is not a pair".
 ***************
-*** 4004,4019 ****
+*** 4014,4029 ****
   6.mo:Expected error in mat pretty-print: "incorrect argument count in call (pretty-format (quote foo) (quote x) (quote x))".
   6.mo:Expected error in mat pretty-print: "pretty-format: 3 is not a symbol".
   6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
@@ -213,9 +213,9 @@
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "abc~s" in call to fprintf at line 1, char 29 of testfile.ss".
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too many arguments for control string "~%~abc~adef~ag~s~~~%" in call to fprintf at line 1, char 29 of testfile.ss".
   6.mo:Expected error in mat print-parameters: "write: cycle detected; proceeding with (print-graph #t)".
---- 4010,4019 ----
+--- 4020,4029 ----
 ***************
-*** 6959,6965 ****
+*** 6969,6975 ****
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in include: failed for testfile-mc-1a.ss: no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: failed for "testfile-mc-1a.ss": no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: file "testfile-mc-1a.ss" not found in source directories
@@ -223,7 +223,7 @@
   7.mo:Expected error in mat eval: "interpret: 7 is not an environment".
   7.mo:Expected error in mat eval: "compile: 7 is not an environment".
   7.mo:Expected error in mat expand: "sc-expand: 7 is not an environment".
---- 6959,6965 ----
+--- 6969,6975 ----
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in include: failed for testfile-mc-1a.ss: no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: failed for "testfile-mc-1a.ss": no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: file "testfile-mc-1a.ss" not found in source directories
@@ -232,7 +232,7 @@
   7.mo:Expected error in mat eval: "compile: 7 is not an environment".
   7.mo:Expected error in mat expand: "sc-expand: 7 is not an environment".
 ***************
-*** 7286,7292 ****
+*** 7296,7302 ****
   record.mo:Expected error in mat record25: "invalid value #\9 for foreign type uptr".
   record.mo:Expected error in mat record25: "invalid value 10 for foreign type float".
   record.mo:Expected error in mat record25: "invalid value 11.0+0.0i for foreign type double".
@@ -240,7 +240,7 @@
   record.mo:Expected error in mat record25: "invalid value 12.0 for foreign type long-long".
   record.mo:Expected error in mat record25: "invalid value 13.0 for foreign type unsigned-long-long".
   record.mo:Expected error in mat record25: "invalid value 3.0 for foreign type int".
---- 7286,7292 ----
+--- 7296,7302 ----
   record.mo:Expected error in mat record25: "invalid value #\9 for foreign type uptr".
   record.mo:Expected error in mat record25: "invalid value 10 for foreign type float".
   record.mo:Expected error in mat record25: "invalid value 11.0+0.0i for foreign type double".
@@ -249,7 +249,7 @@
   record.mo:Expected error in mat record25: "invalid value 13.0 for foreign type unsigned-long-long".
   record.mo:Expected error in mat record25: "invalid value 3.0 for foreign type int".
 ***************
-*** 8461,8473 ****
+*** 8485,8497 ****
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -263,7 +263,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
---- 8461,8473 ----
+--- 8485,8497 ----
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -278,7 +278,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
 ***************
-*** 9224,9248 ****
+*** 9248,9272 ****
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
@@ -304,7 +304,7 @@
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure argument type specifier booleen".
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure argument type specifier integer-34".
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure result type specifier chare".
---- 9224,9248 ----
+--- 9248,9272 ----
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
   foreign.mo:Expected error in mat foreign-procedure: "foreign-procedure: invalid foreign procedure handle foo".
@@ -331,7 +331,7 @@
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure argument type specifier integer-34".
   foreign.mo:Expected error in mat foreign-procedure: "invalid foreign-procedure result type specifier chare".
 ***************
-*** 9255,9286 ****
+*** 9279,9310 ****
   foreign.mo:Expected error in mat foreign-sizeof: "incorrect argument count in call (foreign-sizeof (quote int) (quote int))".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier i-am-not-a-type".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier 1".
@@ -364,7 +364,7 @@
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
---- 9255,9286 ----
+--- 9279,9310 ----
   foreign.mo:Expected error in mat foreign-sizeof: "incorrect argument count in call (foreign-sizeof (quote int) (quote int))".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier i-am-not-a-type".
   foreign.mo:Expected error in mat foreign-sizeof: "foreign-sizeof: invalid foreign type specifier 1".
@@ -398,7 +398,7 @@
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
 ***************
-*** 9288,9313 ****
+*** 9312,9337 ****
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
@@ -425,7 +425,7 @@
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
---- 9288,9313 ----
+--- 9312,9337 ----
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
   foreign.mo:Expected error in mat foreign-strings: "foreign-callable: invalid return value ("ello" 4) from #<procedure>".
@@ -453,7 +453,7 @@
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
 ***************
-*** 9318,9352 ****
+*** 9342,9376 ****
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
@@ -489,7 +489,7 @@
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
---- 9318,9352 ----
+--- 9342,9376 ----
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
   foreign.mo:Expected error in mat foreign-fixed-types: "foreign-callable: invalid return value (- x 7) from #<procedure>".
@@ -526,7 +526,7 @@
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
   foreign.mo:Expected error in mat foreign-C-types: "foreign-callable: invalid return value (73 74) from #<procedure>".
 ***************
-*** 9939,9948 ****
+*** 9963,9972 ****
   exceptions.mo:Expected error in mat assert: "failed assertion (memq (quote b) (quote (1 2 a 3 4)))".
   exceptions.mo:Expected error in mat assert: "failed assertion (q ...)".
   exceptions.mo:Expected error in mat assert: "failed assertion (andmap symbol? (syntax (x ...)))".
@@ -537,7 +537,7 @@
   oop.mo:Expected error in mat oop: "m1: not applicable to 17".
   oop.mo:Expected error in mat oop: "variable <a>-x1 is not bound".
   oop.mo:Expected error in mat oop: "variable <a>-x1-set! is not bound".
---- 9939,9948 ----
+--- 9963,9972 ----
   exceptions.mo:Expected error in mat assert: "failed assertion (memq (quote b) (quote (1 2 a 3 4)))".
   exceptions.mo:Expected error in mat assert: "failed assertion (q ...)".
   exceptions.mo:Expected error in mat assert: "failed assertion (andmap symbol? (syntax (x ...)))".
diff --git a/mats/patch-interpret-0-f-t-f b/mats/patch-interpret-0-f-t-f
index 17e3f0d364..0bc80db5c8 100644
--- a/mats/patch-interpret-0-f-t-f
+++ b/mats/patch-interpret-0-f-t-f
@@ -1,5 +1,5 @@
-*** errors-compile-0-f-t-f	2017-06-08 01:38:37.000000000 -0400
---- errors-interpret-0-f-t-f	2017-06-08 02:00:50.000000000 -0400
+*** errors-compile-0-f-t-f	2017-07-06 19:50:33.000000000 -0600
+--- errors-interpret-0-f-t-f	2017-07-06 20:18:46.000000000 -0600
 ***************
 *** 1,7 ****
   primvars.mo:Expected error in mat make-parameter: "make-parameter: 2 is not a procedure".
@@ -169,7 +169,7 @@
   3.mo:Expected error in mat letrec: "variable f is not bound".
   3.mo:Expected error in mat letrec: "attempt to reference undefined variable a".
 ***************
-*** 4004,4019 ****
+*** 4014,4029 ****
   6.mo:Expected error in mat pretty-print: "incorrect argument count in call (pretty-format (quote foo) (quote x) (quote x))".
   6.mo:Expected error in mat pretty-print: "pretty-format: 3 is not a symbol".
   6.mo:Expected error in mat pretty-print: "pretty-format: invalid format (bad 0 ... ... 0 format)".
@@ -186,9 +186,9 @@
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too few arguments for control string "abc~s" in call to fprintf at line 1, char 29 of testfile.ss".
   6.mo:Expected warning in mat cp1in-verify-format-warnings: "compile: too many arguments for control string "~%~abc~adef~ag~s~~~%" in call to fprintf at line 1, char 29 of testfile.ss".
   6.mo:Expected error in mat print-parameters: "write: cycle detected; proceeding with (print-graph #t)".
---- 4010,4019 ----
+--- 4020,4029 ----
 ***************
-*** 6959,6965 ****
+*** 6969,6975 ****
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in include: failed for testfile-mc-1a.ss: no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: failed for "testfile-mc-1a.ss": no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: file "testfile-mc-1a.ss" not found in source directories
@@ -196,7 +196,7 @@
   7.mo:Expected error in mat eval: "interpret: 7 is not an environment".
   7.mo:Expected error in mat eval: "compile: 7 is not an environment".
   7.mo:Expected error in mat expand: "sc-expand: 7 is not an environment".
---- 6959,6965 ----
+--- 6969,6975 ----
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in include: failed for testfile-mc-1a.ss: no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: failed for "testfile-mc-1a.ss": no such file or directory
   7.mo:Expected error in mat maybe-compile: "separate-compile: Exception in maybe-compile-library: file "testfile-mc-1a.ss" not found in source directories
@@ -205,7 +205,7 @@
   7.mo:Expected error in mat eval: "compile: 7 is not an environment".
   7.mo:Expected error in mat expand: "sc-expand: 7 is not an environment".
 ***************
-*** 7095,7102 ****
+*** 7105,7112 ****
   7.mo:Expected error in mat bytes-allocated: "bytes-allocated: invalid space gnu".
   7.mo:Expected error in mat error: "a: hit me!".
   7.mo:Expected error in mat error: "f: n is 0".
@@ -214,7 +214,7 @@
   record.mo:Expected error in mat record2: "invalid value 3 for foreign type double-float".
   record.mo:Expected error in mat record2: "3 is not of type #<record type fudge>".
   record.mo:Expected error in mat record2: "make-record-type: invalid field list ((immutable double-float a) . b)".
---- 7095,7102 ----
+--- 7105,7112 ----
   7.mo:Expected error in mat bytes-allocated: "bytes-allocated: invalid space gnu".
   7.mo:Expected error in mat error: "a: hit me!".
   7.mo:Expected error in mat error: "f: n is 0".
@@ -224,7 +224,7 @@
   record.mo:Expected error in mat record2: "3 is not of type #<record type fudge>".
   record.mo:Expected error in mat record2: "make-record-type: invalid field list ((immutable double-float a) . b)".
 ***************
-*** 7104,7118 ****
+*** 7114,7128 ****
   record.mo:Expected error in mat type-descriptor: "invalid syntax (type-descriptor 3)".
   record.mo:Expected error in mat type-descriptor: "type-descriptor: unrecognized record car".
   record.mo:Expected error in mat record3: "variable set-fudge-a! is not bound".
@@ -240,7 +240,7 @@
   record.mo:Expected error in mat record9: "record-reader: invalid input #f".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
---- 7104,7118 ----
+--- 7114,7128 ----
   record.mo:Expected error in mat type-descriptor: "invalid syntax (type-descriptor 3)".
   record.mo:Expected error in mat type-descriptor: "type-descriptor: unrecognized record car".
   record.mo:Expected error in mat record3: "variable set-fudge-a! is not bound".
@@ -257,7 +257,7 @@
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
   record.mo:Expected error in mat record9: "record-reader: invalid second argument fudge".
 ***************
-*** 7125,7150 ****
+*** 7135,7160 ****
   record.mo:Expected error in mat record10: "read: unresolvable cycle constructing record of type #<record type bar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
@@ -284,7 +284,7 @@
   record.mo:Expected error in mat foreign-data: "foreign-alloc: 0 is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: <int> is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: -5 is not a positive fixnum".
---- 7125,7150 ----
+--- 7135,7160 ----
   record.mo:Expected error in mat record10: "read: unresolvable cycle constructing record of type #<record type bar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
   record.mo:Expected error in mat record16: "read: unresolvable cycle constructing record of type #<record type bazar> at char 3 of #<input port string>".
@@ -312,7 +312,7 @@
   record.mo:Expected error in mat foreign-data: "foreign-alloc: <int> is not a positive fixnum".
   record.mo:Expected error in mat foreign-data: "foreign-alloc: -5 is not a positive fixnum".
 ***************
-*** 7275,7313 ****
+*** 7285,7323 ****
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record23: "make-record-type: cannot extend sealed record type #<record type foo>".
@@ -352,7 +352,7 @@
   record.mo:Expected error in mat record?: "record?: 4 is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: a is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: #(1) is not a record type descriptor".
---- 7275,7313 ----
+--- 7285,7323 ----
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record22: "invalid field specifier (immutable creepy q)".
   record.mo:Expected error in mat record23: "make-record-type: cannot extend sealed record type #<record type foo>".
@@ -393,7 +393,7 @@
   record.mo:Expected error in mat record?: "record?: a is not a record type descriptor".
   record.mo:Expected error in mat record?: "record?: #(1) is not a record type descriptor".
 ***************
-*** 7322,7378 ****
+*** 7332,7388 ****
   record.mo:Expected error in mat r6rs-records-procedural: "make-record-constructor-descriptor: invalid protocol flimflam".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure not-a-procedure".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure spam".
@@ -451,7 +451,7 @@
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "cannot extend define-record-type parent fratrat".
---- 7322,7378 ----
+--- 7332,7388 ----
   record.mo:Expected error in mat r6rs-records-procedural: "make-record-constructor-descriptor: invalid protocol flimflam".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure not-a-procedure".
   record.mo:Expected error in mat r6rs-records-procedural: "attempt to apply non-procedure spam".
@@ -510,7 +510,7 @@
   record.mo:Expected error in mat r6rs-records-syntactic: "define-record-type: incompatible record type cpoint - different parent".
   record.mo:Expected error in mat r6rs-records-syntactic: "cannot extend define-record-type parent fratrat".
 ***************
-*** 8461,8473 ****
+*** 8485,8497 ****
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -524,7 +524,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
---- 8461,8473 ----
+--- 8485,8497 ----
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx-: "fx-: #f is not a fixnum".
   fx.mo:Expected error in mat fx*: "fx*: (a . b) is not a fixnum".
@@ -539,7 +539,7 @@
   fx.mo:Expected error in mat r6rs:fx*: "fx*: <-int> is not a fixnum".
   fx.mo:Expected error in mat r6rs:fx*: "fx*: #f is not a fixnum".
 ***************
-*** 9939,9948 ****
+*** 9963,9972 ****
   exceptions.mo:Expected error in mat assert: "failed assertion (memq (quote b) (quote (1 2 a 3 4)))".
   exceptions.mo:Expected error in mat assert: "failed assertion (q ...)".
   exceptions.mo:Expected error in mat assert: "failed assertion (andmap symbol? (syntax (x ...)))".
@@ -550,7 +550,7 @@
   oop.mo:Expected error in mat oop: "m1: not applicable to 17".
   oop.mo:Expected error in mat oop: "variable <a>-x1 is not bound".
   oop.mo:Expected error in mat oop: "variable <a>-x1-set! is not bound".
---- 9939,9948 ----
+--- 9963,9972 ----
   exceptions.mo:Expected error in mat assert: "failed assertion (memq (quote b) (quote (1 2 a 3 4)))".
   exceptions.mo:Expected error in mat assert: "failed assertion (q ...)".
   exceptions.mo:Expected error in mat assert: "failed assertion (andmap symbol? (syntax (x ...)))".
diff --git a/mats/patch-interpret-3-f-f-f b/mats/patch-interpret-3-f-f-f
index 47d2dcead4..77ffa052c7 100644
--- a/mats/patch-interpret-3-f-f-f
+++ b/mats/patch-interpret-3-f-f-f
@@ -1,5 +1,5 @@
-*** errors-compile-3-f-f-f	2017-06-08 01:35:00.000000000 -0400
---- errors-interpret-3-f-f-f	2017-06-08 02:15:41.000000000 -0400
+*** errors-compile-3-f-f-f	2017-07-06 19:46:12.000000000 -0600
+--- errors-interpret-3-f-f-f	2017-07-06 20:38:59.000000000 -0600
 ***************
 *** 1,3 ****
 --- 1,9 ----
diff --git a/mats/patch-interpret-3-f-t-f b/mats/patch-interpret-3-f-t-f
index 7f05db4eb3..b085b34992 100644
--- a/mats/patch-interpret-3-f-t-f
+++ b/mats/patch-interpret-3-f-t-f
@@ -1,5 +1,5 @@
-*** errors-compile-3-f-t-f	2017-06-08 01:42:09.000000000 -0400
---- errors-interpret-3-f-t-f	2017-06-08 02:04:33.000000000 -0400
+*** errors-compile-3-f-t-f	2017-07-06 19:54:42.000000000 -0600
+--- errors-interpret-3-f-t-f	2017-07-06 20:23:52.000000000 -0600
 ***************
 *** 1,3 ****
 --- 1,9 ----
diff --git a/mats/root-experr-compile-0-f-f-f b/mats/root-experr-compile-0-f-f-f
index 503bbb6127..25e8e083f0 100644
--- a/mats/root-experr-compile-0-f-f-f
+++ b/mats/root-experr-compile-0-f-f-f
@@ -7506,6 +7506,9 @@ hash.mo:Expected error in mat hashtable-arguments: "hashtable-equivalence-functi
 hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-weak?)".
 hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-weak? $ht 3)".
 hash.mo:Expected error in mat hashtable-arguments: "hashtable-weak?: (hash . table) is not a hashtable".
+hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-ephemeron?)".
+hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-ephemeron? $ht 3)".
+hash.mo:Expected error in mat hashtable-arguments: "hashtable-ephemeron?: (hash . table) is not a hashtable".
 hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value "oops" for any".
 hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value 3.5 for any".
 hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value 1+2i for any".
@@ -7528,6 +7531,10 @@ hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count
 hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument -1".
 hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument #t".
 hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument #f".
+hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (make-ephemeron-eq-hashtable 3 #t)".
+hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument -1".
+hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument #t".
+hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument #f".
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref)".
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref $wht)".
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref $wht (quote a))".
@@ -7563,6 +7570,9 @@ hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-cell: (hash
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-weak?)".
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-weak? $ht 3)".
 hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-weak?: (hash . table) is not an eq hashtable".
+hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ephemeron?)".
+hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ephemeron? $ht 3)".
+hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-ephemeron?: (hash . table) is not an eq hashtable".
 hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref)".
 hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref $symht)".
 hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref $symht (quote a))".
@@ -7617,6 +7627,10 @@ hash.mo:Expected error in mat eqv-hashtable-arguments: "incorrect argument count
 hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument -1".
 hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #t".
 hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #f".
+hash.mo:Expected error in mat eqv-hashtable-arguments: "incorrect argument count in call (make-ephemeron-eqv-hashtable 3 #t)".
+hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument -1".
+hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument #t".
+hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument #f".
 hash.mo:Expected error in mat generic-hashtable: "hashtable-clear!: #<hashtable> is not mutable".
 hash.mo:Expected error in mat generic-hashtable: "hashtable-delete!: #<hashtable> is not mutable".
 hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
diff --git a/mats/root-experr-compile-2-f-f-f b/mats/root-experr-compile-2-f-f-f
index 503bbb6127..25e8e083f0 100644
--- a/mats/root-experr-compile-2-f-f-f
+++ b/mats/root-experr-compile-2-f-f-f
@@ -7506,6 +7506,9 @@ hash.mo:Expected error in mat hashtable-arguments: "hashtable-equivalence-functi
 hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-weak?)".
 hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-weak? $ht 3)".
 hash.mo:Expected error in mat hashtable-arguments: "hashtable-weak?: (hash . table) is not a hashtable".
+hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-ephemeron?)".
+hash.mo:Expected error in mat hashtable-arguments: "incorrect argument count in call (hashtable-ephemeron? $ht 3)".
+hash.mo:Expected error in mat hashtable-arguments: "hashtable-ephemeron?: (hash . table) is not a hashtable".
 hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value "oops" for any".
 hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value 3.5 for any".
 hash.mo:Expected error in mat hash-return-value: "hashtable-ref: invalid hash-function #<procedure> return value 1+2i for any".
@@ -7528,6 +7531,10 @@ hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count
 hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument -1".
 hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument #t".
 hash.mo:Expected error in mat eq-hashtable-arguments: "make-weak-eq-hashtable: invalid size argument #f".
+hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (make-ephemeron-eq-hashtable 3 #t)".
+hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument -1".
+hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument #t".
+hash.mo:Expected error in mat eq-hashtable-arguments: "make-ephemeron-eq-hashtable: invalid size argument #f".
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref)".
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref $wht)".
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ref $wht (quote a))".
@@ -7563,6 +7570,9 @@ hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-cell: (hash
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-weak?)".
 hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-weak? $ht 3)".
 hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-weak?: (hash . table) is not an eq hashtable".
+hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ephemeron?)".
+hash.mo:Expected error in mat eq-hashtable-arguments: "incorrect argument count in call (eq-hashtable-ephemeron? $ht 3)".
+hash.mo:Expected error in mat eq-hashtable-arguments: "eq-hashtable-ephemeron?: (hash . table) is not an eq hashtable".
 hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref)".
 hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref $symht)".
 hash.mo:Expected error in mat symbol-hashtable-arguments: "incorrect argument count in call (symbol-hashtable-ref $symht (quote a))".
@@ -7617,6 +7627,10 @@ hash.mo:Expected error in mat eqv-hashtable-arguments: "incorrect argument count
 hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument -1".
 hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #t".
 hash.mo:Expected error in mat eqv-hashtable-arguments: "make-weak-eqv-hashtable: invalid size argument #f".
+hash.mo:Expected error in mat eqv-hashtable-arguments: "incorrect argument count in call (make-ephemeron-eqv-hashtable 3 #t)".
+hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument -1".
+hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument #t".
+hash.mo:Expected error in mat eqv-hashtable-arguments: "make-ephemeron-eqv-hashtable: invalid size argument #f".
 hash.mo:Expected error in mat generic-hashtable: "hashtable-clear!: #<hashtable> is not mutable".
 hash.mo:Expected error in mat generic-hashtable: "hashtable-delete!: #<hashtable> is not mutable".
 hash.mo:Expected error in mat generic-hashtable: "hashtable-update!: #<hashtable> is not mutable".
diff --git a/release_notes/release_notes.stex b/release_notes/release_notes.stex
index b484eab0a2..4a0bef3672 100644
--- a/release_notes/release_notes.stex
+++ b/release_notes/release_notes.stex
@@ -78,6 +78,19 @@ procedures.
 Immutable boxes are created via \scheme{box-immutable}.
 Any attempt to modify an immutable object causes an exception to be raised.
 
+\subsection{Ephemeron pairs and hashtables (9.4.1)}
+
+Support for ephemeron pairs has been added, along with eq and eqv
+hashtables that use ephemeron pairs to combine keys and values. An
+ephemeron pair avoids the ``key in value'' problem of weak pairs,
+where a weakly held key is paired to a value that refers back to the
+key, in which case the key remains reachable as long as the pair is
+reachable. In an ephemeron pair, the cdr of the pair is not considered
+reachable by the garbage collector until both the pair and the car of
+the pair have been found reachable. An ephemeron hashtable implements
+a weak mapping where referencing a key in a value does not prevent the
+mapping from being removed from the table.
+
 \subsection{Optional timeout for \protect\scheme{condition-wait} (9.4.1)}
 
 The \scheme{condition-wait} procedure now takes an optional
diff --git a/s/cmacros.ss b/s/cmacros.ss
index 003260cf90..7c57bffe4e 100644
--- a/s/cmacros.ss
+++ b/s/cmacros.ss
@@ -1845,6 +1845,10 @@
 
 (define-constant hashtable-default-size 8)
 
+(define-constant eq-hashtable-subtype-normal 0)
+(define-constant eq-hashtable-subtype-weak 1)
+(define-constant eq-hashtable-subtype-ephemeron 2)
+
 ; keep in sync with make-date
 (define-constant dtvec-nsec 0)
 (define-constant dtvec-sec 1)
diff --git a/s/cpnanopass.ss b/s/cpnanopass.ss
index 512533a979..601a510db0 100644
--- a/s/cpnanopass.ss
+++ b/s/cpnanopass.ss
@@ -8940,11 +8940,11 @@
                [(quote ,d) (and (and (fixnum? d) (fx<= d 4)) (add-cdrs d e-ls))]
                [else #f])]))
         (let ()
-          (define (go0 src sexpr weak?)
+          (define (go0 src sexpr subtype)
             (%primcall src sexpr $make-eq-hashtable
               (immediate ,(fix (constant hashtable-default-size)))
-              (immediate ,weak?)))
-          (define (go1 src sexpr e-size weak?)
+              (immediate ,(fix subtype))))
+          (define (go1 src sexpr e-size subtype)
             (nanopass-case (L7 Expr) e-size
               [(quote ,d)
                ; d must be a fixnum? for $hashtable-size-minlen and a
@@ -8952,14 +8952,17 @@
                (and (and (fixnum? d) (target-fixnum? d) (fx>= d 0))
                     (%primcall src sexpr $make-eq-hashtable
                       (immediate ,(fix ($hashtable-size->minlen d)))
-                      (immediate ,weak?)))]
+                      (immediate ,(fix subtype))))]
               [else #f]))
           (define-inline 3 make-eq-hashtable
-            [() (go0 src sexpr (constant sfalse))]
-            [(e-size) (go1 src sexpr e-size (constant sfalse))])
+            [() (go0 src sexpr (constant eq-hashtable-subtype-normal))]
+            [(e-size) (go1 src sexpr e-size (constant eq-hashtable-subtype-normal))])
           (define-inline 3 make-weak-eq-hashtable
-            [() (go0 src sexpr (constant strue))]
-            [(e-size) (go1 src sexpr e-size (constant strue))]))
+            [() (go0 src sexpr (constant eq-hashtable-subtype-weak))]
+            [(e-size) (go1 src sexpr e-size (constant eq-hashtable-subtype-weak))])
+          (define-inline 3 make-ephemeron-eq-hashtable
+            [() (go0 src sexpr (constant eq-hashtable-subtype-ephemeron))]
+            [(e-size) (go1 src sexpr e-size (constant eq-hashtable-subtype-ephemeron))]))
         (let ()
           (define-syntax def-put-x
             (syntax-rules ()
diff --git a/s/fasl.ss b/s/fasl.ss
index 5c96969482..be4eaefd86 100644
--- a/s/fasl.ss
+++ b/s/fasl.ss
@@ -432,7 +432,10 @@
   (lambda (x p t a?)
     (put-u8 p (constant fasl-type-eq-hashtable))
     (put-u8 p (if (hashtable-mutable? x) 1 0))
-    (put-u8 p (if (eq-hashtable-weak? x) 1 0))
+    (put-u8 p (cond
+               [(eq-hashtable-weak? x) (constant eq-hashtable-subtype-weak)]
+               [(eq-hashtable-ephemeron? x) (constant eq-hashtable-subtype-ephemeron)]
+               [else  (constant eq-hashtable-subtype-normal)]))
     (put-uptr p ($ht-minlen x))
     (put-uptr p ($ht-veclen x))
     (let-values ([(keyvec valvec) (hashtable-entries x)])
diff --git a/s/hashtable-types.ss b/s/hashtable-types.ss
index 3b7ffb5048..e805f5492e 100644
--- a/s/hashtable-types.ss
+++ b/s/hashtable-types.ss
@@ -24,8 +24,8 @@
 
 (define-record-type eq-ht
   (parent ht)
-  (fields (immutable weak?))
-  (nongenerative #{eq-ht bu811z2onf9o6tfc-5})
+  (fields (immutable subtype)) ; eq-hashtable-subtype-{normal,weak,ephemeron}
+  (nongenerative #{eq-ht icguu8mlhm1y7ywsairxck-0})
   (sealed #t))
 
 (define-record-type symbol-ht
diff --git a/s/library.ss b/s/library.ss
index 9ae9d5da2b..5f9c2d7381 100644
--- a/s/library.ss
+++ b/s/library.ss
@@ -1435,7 +1435,11 @@
              [b (vector-ref vec idx)])
         (lookup-keyval x b
           values
-          (let ([keyval (if (eq-ht-weak? h) (ephemeron-cons x v) (cons x v))])
+          (let ([keyval (let ([subtype (eq-ht-subtype h)])
+                          (cond
+                           [(eq? subtype (constant eq-hashtable-subtype-normal)) (cons x v)]
+                           [(eq? subtype (constant eq-hashtable-subtype-weak)) (weak-cons x v)]
+                           [else (ephemeron-cons x v)]))])
             (vector-set! vec idx ($make-tlc h keyval b))
             (incr-size! h vec)
             keyval))))
@@ -1451,7 +1455,11 @@
               (begin
                 (vector-set! vec idx
                   ($make-tlc h
-                    (if (eq-ht-weak? h) (ephemeron-cons x v) (cons x v))
+                    (let ([subtype (eq-ht-subtype h)])
+                      (cond
+                       [(eq? subtype (constant eq-hashtable-subtype-normal)) (cons x v)]
+                       [(eq? subtype (constant eq-hashtable-subtype-weak)) (weak-cons x v)]
+                       [else (ephemeron-cons x v)]))
                     b))
                 (incr-size! h vec))))))
   
diff --git a/s/newhash.ss b/s/newhash.ss
index de59fe70ba..9348043096 100644
--- a/s/newhash.ss
+++ b/s/newhash.ss
@@ -61,6 +61,7 @@ Documentation notes:
 ;;; other generic hash operators
 (define hashtable-cell)
 (define hashtable-weak?)                 ; hashtable
+(define hashtable-ephemeron?)            ; hashtable
 
 ;;; eq-hashtable operators
 (define make-weak-eq-hashtable)          ; [k], k >= 0
@@ -71,6 +72,7 @@ Documentation notes:
 (define eq-hashtable-cell)               ; eq-hashtable key default
 (define eq-hashtable-delete!)            ; eq-hashtable key
 (define eq-hashtable-weak?)              ; eq-hashtable
+(define eq-hashtable-ephemeron?)         ; eq-hashtable
 
 ;;; eq-hashtable operators
 (define make-symbol-hashtable)           ; [k], k >= 0
@@ -85,7 +87,7 @@ Documentation notes:
 (define make-weak-eqv-hashtable)         ; [k], k >= 0
   
 ;;; unsafe eq-hashtable operators
-(define $make-eq-hashtable)              ; fxminlen weak?, fxminlen = 2^n, n >= 0
+(define $make-eq-hashtable)              ; fxminlen subtype, fxminlen = 2^n, n >= 0
 (define $eq-hashtable-keys)              ; eq-hashtable
 (define $eq-hashtable-values)            ; eq-hashtable
 (define $eq-hashtable-entries)           ; eq-hashtable
@@ -393,8 +395,8 @@ Documentation notes:
         [else (logxor (lognot (number-hash (real-part z))) (number-hash (imag-part z)))])))
 
   (set! $make-eq-hashtable ; assumes minlen is a power of two >= 1
-    (lambda (minlen weak?)
-      (make-eq-ht 'eq #t ($make-eqhash-vector minlen) minlen 0 weak?)))
+    (lambda (minlen subtype)
+      (make-eq-ht 'eq #t ($make-eqhash-vector minlen) minlen 0 subtype)))
 
   (set-who! $hashtable-veclen
     (lambda (h)
@@ -444,8 +446,11 @@ Documentation notes:
  ; csv7 interface
   (set! make-hash-table
     (case-lambda
-      [() ($make-eq-hashtable (constant hashtable-default-size) #f)]
-      [(weak?) ($make-eq-hashtable (constant hashtable-default-size) weak?)]))
+      [() ($make-eq-hashtable (constant hashtable-default-size) (constant eq-hashtable-subtype-normal))]
+      [(weak?) ($make-eq-hashtable (constant hashtable-default-size)
+                                   (if weak?
+                                       (constant eq-hashtable-subtype-weak)
+                                       (constant eq-hashtable-subtype-normal)))]))
 
   (set! hash-table?
     (lambda (x)
@@ -488,13 +493,18 @@ Documentation notes:
 
   (set-who! make-eq-hashtable
     (case-lambda
-      [() ($make-eq-hashtable (constant hashtable-default-size) #f)]
-      [(k) ($make-eq-hashtable (size->minlen who k) #f)]))
+      [() ($make-eq-hashtable (constant hashtable-default-size) (constant eq-hashtable-subtype-normal))]
+      [(k) ($make-eq-hashtable (size->minlen who k) (constant eq-hashtable-subtype-normal))]))
 
   (set-who! make-weak-eq-hashtable
     (case-lambda
-      [() ($make-eq-hashtable (constant hashtable-default-size) #t)]
-      [(k) ($make-eq-hashtable (size->minlen who k) #t)]))
+      [() ($make-eq-hashtable (constant hashtable-default-size) (constant eq-hashtable-subtype-weak))]
+      [(k) ($make-eq-hashtable (size->minlen who k) (constant eq-hashtable-subtype-weak))]))
+
+  (set-who! make-ephemeron-eq-hashtable
+    (case-lambda
+      [() ($make-eq-hashtable (constant hashtable-default-size) (constant eq-hashtable-subtype-ephemeron))]
+      [(k) ($make-eq-hashtable (size->minlen who k) (constant eq-hashtable-subtype-ephemeron))]))
 
   (let ()
     (define $make-hashtable
@@ -507,9 +517,9 @@ Documentation notes:
             (make-symbol-ht 'symbol #t (make-vector minlen '()) minlen 0 equiv?)
             (make-gen-ht 'generic #t (make-vector minlen '()) minlen 0 hash equiv?))))
     (define $make-eqv-hashtable
-      (lambda (minlen weak?)
+      (lambda (minlen subtype)
         (make-eqv-ht 'eqv #t
-          ($make-eq-hashtable minlen weak?)
+          ($make-eq-hashtable minlen subtype)
           ($make-hashtable minlen number-hash eqv?))))
     (set-who! make-hashtable
       (case-lambda
@@ -523,12 +533,16 @@ Documentation notes:
          ($make-hashtable (size->minlen who k) hash equiv?)]))
     (set-who! make-eqv-hashtable
       (case-lambda
-        [() ($make-eqv-hashtable (constant hashtable-default-size) #f)]
-        [(k) ($make-eqv-hashtable (size->minlen who k) #f)]))
+        [() ($make-eqv-hashtable (constant hashtable-default-size) (constant eq-hashtable-subtype-normal))]
+        [(k) ($make-eqv-hashtable (size->minlen who k) (constant eq-hashtable-subtype-normal))]))
     (set-who! make-weak-eqv-hashtable
       (case-lambda
-        [() ($make-eqv-hashtable (constant hashtable-default-size) #t)]
-        [(k) ($make-eqv-hashtable (size->minlen who k) #t)])))
+        [() ($make-eqv-hashtable (constant hashtable-default-size) (constant eq-hashtable-subtype-weak))]
+        [(k) ($make-eqv-hashtable (size->minlen who k) (constant eq-hashtable-subtype-weak))]))
+    (set-who! make-ephemeron-eqv-hashtable
+      (case-lambda
+        [() ($make-eqv-hashtable (constant hashtable-default-size) (constant eq-hashtable-subtype-ephemeron))]
+        [(k) ($make-eqv-hashtable (size->minlen who k) (constant eq-hashtable-subtype-ephemeron))])))
 
   (set! eq-hashtable-ref
     (lambda (h x v)
@@ -577,14 +591,27 @@ Documentation notes:
   (set-who! eq-hashtable-weak?
     (lambda (h)
       (unless (eq-ht? h) ($oops who "~s is not an eq hashtable" h))
-      (eq-ht-weak? h)))
+      (eq? (constant eq-hashtable-subtype-weak) (eq-ht-subtype h))))
+
+  (set-who! eq-hashtable-ephemeron?
+    (lambda (h)
+      (unless (eq-ht? h) ($oops who "~s is not an eq hashtable" h))
+      (eq? (constant eq-hashtable-subtype-ephemeron) (eq-ht-subtype h))))
 
   (set-who! hashtable-weak?
     (lambda (h)
       (unless (xht? h) ($oops who "~s is not a hashtable" h))
       (case (xht-type h)
-        [(eq) (eq-ht-weak? h)]
-        [(eqv) (eq-ht-weak? (eqv-ht-eqht h))]
+        [(eq) (eq? (constant eq-hashtable-subtype-weak) (eq-ht-subtype h))]
+        [(eqv) (eq? (constant eq-hashtable-subtype-weak) (eq-ht-subtype (eqv-ht-eqht h)))]
+        [else #f])))
+
+  (set-who! hashtable-ephemeron?
+    (lambda (h)
+      (unless (xht? h) ($oops who "~s is not a hashtable" h))
+      (case (xht-type h)
+        [(eq) (eq? (constant eq-hashtable-subtype-ephemeron) (eq-ht-subtype h))]
+        [(eqv) (eq? (constant eq-hashtable-subtype-ephemeron) (eq-ht-subtype (eqv-ht-eqht h)))]
         [else #f])))
 
   (set-who! symbol-hashtable-ref
@@ -1004,11 +1031,11 @@ Documentation notes:
 
   (set! $eq-hashtable-copy
     (lambda (h1 mutable?)
-      (let ([weak? (eq-ht-weak? h1)])
+      (let ([subtype (eq-ht-subtype h1)])
         (let* ([vec1 (ht-vec h1)]
                [n (vector-length vec1)]
                [vec2 ($make-eqhash-vector n)]
-               [h2 (make-eq-ht 'eq mutable? vec2 (ht-minlen h1) (ht-size h1) weak?)])
+               [h2 (make-eq-ht 'eq mutable? vec2 (ht-minlen h1) (ht-size h1) subtype)])
           (let outer ([i 0])
             (if (fx= i n)
                 h2
@@ -1019,7 +1046,10 @@ Documentation notes:
                           b
                           ($make-tlc h2
                             (let* ([keyval ($tlc-keyval b)] [key (car keyval)] [val (cdr keyval)])
-                              (if weak?  (ephemeron-cons key val) (cons key val)))
+                              (cond
+                               [(eq? subtype (constant eq-hashtable-subtype-normal)) (cons key val)]
+                               [(eq? subtype (constant eq-hashtable-subtype-weak)) (weak-cons key val)]
+                               [else (ephemeron-cons key val)]))
                             (inner ($tlc-next b))))))
                   (outer (fx+ i 1)))))
           h2))))
diff --git a/s/primdata.ss b/s/primdata.ss
index e4e18e0d85..263cd6b206 100644
--- a/s/primdata.ss
+++ b/s/primdata.ss
@@ -1254,6 +1254,7 @@
   (eq-hashtable-cell [sig [(eq-hashtable ptr ptr) -> ((ptr . ptr))]] [flags true])
   (eq-hashtable-contains? [sig [(eq-hashtable ptr) -> (boolean)]] [flags discard])
   (eq-hashtable-delete! [sig [(eq-hashtable ptr) -> (void)]] [flags true])
+  (eq-hashtable-ephemeron? [sig [(eq-hashtable) -> (boolean)]] [flags pure mifoldable discard])
   (eq-hashtable-ref [sig [(eq-hashtable ptr ptr) -> (ptr)]] [flags discard])
   (eq-hashtable-set! [sig [(eq-hashtable ptr ptr) -> (void)]] [flags true])
   (eq-hashtable-update! [sig [(eq-hashtable ptr procedure ptr) -> (void)]] [flags])
@@ -1360,6 +1361,7 @@
   (getenv [sig [(string) -> (maybe-string)]] [flags discard])
   (getprop [sig [(symbol ptr) (symbol ptr ptr) -> (ptr)]] [flags discard])
   (hash-table? [sig [(ptr) -> (boolean)]] [flags pure unrestricted mifoldable discard])
+  (hashtable-ephemeron? [sig [(hashtable) -> (boolean)]] [flags pure mifoldable discard])
   (hash-table-for-each [sig [(old-hash-table procedure) -> (void)]] [flags])
   (hash-table-map [sig [(old-hash-table procedure) -> (list)]] [flags true])
   (hashtable-cell [sig [(old-hash-table ptr ptr) -> ((ptr . ptr))]] [flags true])
@@ -1412,6 +1414,8 @@
   (make-condition [feature pthreads] [sig [() -> (condition-object)]] [flags pure unrestricted alloc])
   (make-continuation-condition [sig [(ptr) -> (condition)]] [flags pure unrestricted mifoldable discard])
   (make-cost-center [sig [() -> (cost-center)]] [flags unrestricted alloc])
+  (make-ephemeron-eq-hashtable [sig [() (uint) -> (eq-hashtable)]] [flags alloc])
+  (make-ephemeron-eqv-hashtable [sig [() (uint) -> (hashtable)]] [flags alloc])
   (make-engine [sig [(procedure) -> (engine)]] [flags pure alloc])
   (make-format-condition [sig [() -> (condition)]] [flags pure unrestricted mifoldable discard])
   (make-fxvector [sig [(length) (length fixnum) -> (fxvector)]] [flags alloc])
diff --git a/s/strip.ss b/s/strip.ss
index c3e990e177..feab33f259 100644
--- a/s/strip.ss
+++ b/s/strip.ss
@@ -33,7 +33,7 @@
     (flonum high low)
     (small-integer iptr)
     (large-integer sign vuptr)
-    (eq-hashtable mutable? weak? minlen veclen vpfasl)
+    (eq-hashtable mutable? subtype minlen veclen vpfasl)
     (symbol-hashtable mutable? minlen equiv veclen vpfasl)
     (code flags free name arity-mask info pinfo* bytes m vreloc)
     (atom ty uptr)
@@ -229,11 +229,11 @@
                    (vector-set! v i (read-uptr p))))))]
           [(fasl-type-eq-hashtable)
            (let* ([mutable? (read-byte p)]
-                  [weak? (read-byte p)]
+                  [subtype (read-byte p)]
                   [minlen (read-uptr p)]
                   [veclen (read-uptr p)]
                   [v (read-vpfasl p g)])
-             (fasl-eq-hashtable mutable? weak? minlen veclen v))]
+             (fasl-eq-hashtable mutable? subtype minlen veclen v))]
           [(fasl-type-symbol-hashtable)
            (let* ([mutable? (read-byte p)]
                   [minlen (read-uptr p)]
@@ -416,7 +416,7 @@
           [flonum (high low) (build-graph! x t void)]
           [small-integer (iptr) (void)]
           [large-integer (sign vuptr) (build-graph! x t void)]
-          [eq-hashtable (mutable? weak? minlen veclen vpfasl)
+          [eq-hashtable (mutable? subtype minlen veclen vpfasl)
            (build-graph! x t
              (lambda ()
                (vector-for-each
@@ -577,12 +577,12 @@
                (write-byte p sign)
                (write-uptr p (vector-length vuptr))
                (vector-for-each (lambda (uptr) (write-uptr p uptr)) vuptr)))]
-          [eq-hashtable (mutable? weak? minlen veclen vpfasl)
+          [eq-hashtable (mutable? subtype minlen veclen vpfasl)
            (write-graph p t x
              (lambda ()
                (write-byte p (constant fasl-type-eq-hashtable))
                (write-byte p mutable?)
-               (write-byte p weak?)
+               (write-byte p subtype)
                (write-uptr p minlen)
                (write-uptr p veclen)
                (write-uptr p (vector-length vpfasl))
@@ -843,9 +843,9 @@
                         (and (eqv? high1 high2)
                              (eqv? low1 low2))]
                        [large-integer (sign vuptr) (and (eqv? sign1 sign2) (vandmap = vuptr1 vuptr2))]
-                       [eq-hashtable (mutable? weak? minlen veclen vpfasl)
+                       [eq-hashtable (mutable? subtype minlen veclen vpfasl)
                         (and (eqv? mutable?1 mutable?2)
-                             (eqv? weak?1 weak?2)
+                             (eqv? subtype1 subtype2)
                              (eqv? minlen1 minlen2)
                              ; don't care if veclens differ
                              #;(eqv? veclen1 veclen2)