diff --git a/c/fasl.c b/c/fasl.c
index b8aef474bf..0386b6ce46 100644
--- a/c/fasl.c
+++ b/c/fasl.c
@@ -405,13 +405,17 @@ static uptr uf_uptrin(unbufFaslFile uf) {
 }
 
 char *S_format_scheme_version(uptr n) {
-  static char buf[16]; INT len;
-  if ((n >> 16) != ((n >> 16) & 0xffff)) return "unknown";
-  if ((n & 0xff) == 0)
-    len = snprintf(buf, 16, "%d.%d", (int) n >> 16, (int) (n >> 8) & 0xff);
-  else
-    len = snprintf(buf, 16, "%d.%d.%d", (int) n >> 16, (int) (n >> 8) & 0xff, 
-                   (int) n & 0xff);
+  static char buf[20]; INT len;
+  if ((n >> 24) != ((n >> 24) & 0xffff)) return "unknown";
+  if ((n & 0xff) == 0) {
+    if ((n & 0xff) == 0)
+      len = snprintf(buf, 20, "%d.%d", (int) n >> 24, (int) (n >> 16) & 0xff);
+    else
+      len = snprintf(buf, 20, "%d.%d.%d", (int) n >> 24, (int) (n >> 16) & 0xff, 
+                     (int) (n >> 8) & 0xff);
+  } else
+    len = snprintf(buf, 20, "%d.%d.%d.%d", (int) n >> 24, (int) (n >> 16) & 0xff, 
+                   (int) (n >> 8) & 0xff, (int) n & 0xff);
   return len > 0 ? buf : "unknown";
 }
 
diff --git a/makefiles/Mf-install.in b/makefiles/Mf-install.in
index 039a6b48fd..9e66ef8711 100644
--- a/makefiles/Mf-install.in
+++ b/makefiles/Mf-install.in
@@ -62,7 +62,7 @@ InstallLZ4Target=
 #                 no changes should be needed below this point                #
 ###############################################################################
 
-Version=csv9.5.3.1
+Version=csv9.5.3.2
 Include=boot/$m
 PetiteBoot=boot/$m/petite.boot
 SchemeBoot=boot/$m/scheme.boot
diff --git a/s/base-lang.ss b/s/base-lang.ss
index 3538ac19d0..585b800385 100644
--- a/s/base-lang.ss
+++ b/s/base-lang.ss
@@ -18,6 +18,7 @@
          sorry! make-preinfo preinfo? preinfo-lambda? preinfo-sexpr preinfo-sexpr-set! preinfo-src
          make-preinfo-lambda preinfo-lambda-name preinfo-lambda-name-set! preinfo-lambda-flags
          preinfo-lambda-flags-set! preinfo-lambda-libspec
+         make-preinfo-call preinfo-call? preinfo-call-check?
          prelex? make-prelex prelex-name prelex-name-set! prelex-flags prelex-flags-set!
          prelex-source prelex-operand prelex-operand-set! prelex-uname make-prelex*
          target-fixnum? target-bignum?)
@@ -183,6 +184,19 @@
           [(src sexpr libspec name) ((pargs->new src sexpr) libspec name 0)]
           [(src sexpr libspec name flags) ((pargs->new src sexpr) libspec name flags)]))))
 
+  (define-record-type preinfo-call
+    (nongenerative #{preinfo-call e23pkvo5btgapnzomqgegm-7})
+    (parent preinfo)
+    (sealed #t)
+    (fields check?)
+    (protocol
+      (lambda (pargs->new)
+        (case-lambda
+          [() ((pargs->new) #t)]
+          [(src) ((pargs->new src) #t)]
+          [(src sexpr) ((pargs->new src sexpr) #t)]
+          [(src sexpr check?) ((pargs->new src sexpr) check?)]))))
+
   ; language of foreign types
   (define-language Ltype 
     (nongenerative-id #{Ltype czp82kxwe75y4e18-1})
diff --git a/s/cmacros.ss b/s/cmacros.ss
index 3b3babf57d..7e1743ff53 100644
--- a/s/cmacros.ss
+++ b/s/cmacros.ss
@@ -328,7 +328,7 @@
                  [(_ foo e1 e2) e1] ...
                  [(_ bar e1 e2) e2]))))])))
 
-(define-constant scheme-version #x09050301)
+(define-constant scheme-version #x09050302)
 
 (define-syntax define-machine-types
   (lambda (x)
diff --git a/s/compile.ss b/s/compile.ss
index c4c0329073..5684d6ae36 100644
--- a/s/compile.ss
+++ b/s/compile.ss
@@ -1098,7 +1098,7 @@
     (define gen-var (lambda (sym) (make-prelex sym 0 #f #f)))
     (define build-let
       (lambda (ids exprs body)
-        `(call ,(make-preinfo) ,(build-lambda ids body) ,exprs ...)))
+        `(call ,(make-preinfo-call) ,(build-lambda ids body) ,exprs ...)))
 
     (define build-lambda
       (lambda (ids body)
@@ -1107,7 +1107,7 @@
 
     (define build-call
       (lambda (e . e*)
-        `(call ,(make-preinfo) ,e ,e* ...)))
+        `(call ,(make-preinfo-call) ,e ,e* ...)))
 
     (define-syntax build-primcall
       ; written as a macro to give lookup-primref a chance to lookup the primref at expansion time
diff --git a/s/cp0.ss b/s/cp0.ss
index cfea61ddbf..d1729f5be4 100644
--- a/s/cp0.ss
+++ b/s/cp0.ss
@@ -673,7 +673,7 @@
     (module (build-primcall)
       (define $build-primcall
         (case-lambda
-          [(primref args) ($build-primcall (make-preinfo) primref args)]
+          [(primref args) ($build-primcall (make-preinfo-call) primref args)]
           [(preinfo primref args) `(call ,preinfo ,primref ,args ...)]))
       (define-syntax build-primcall
         (syntax-rules ()
@@ -718,12 +718,12 @@
     (define build-let
       (case-lambda
         [(lambda-preinfo ids exps body)
-         (build-call (make-preinfo) (build-lambda lambda-preinfo ids body) exps)]
-        [(ids exps body) (build-call (make-preinfo) (build-lambda ids body) exps)]))
+         (build-call (make-preinfo-call) (build-lambda lambda-preinfo ids body) exps)]
+        [(ids exps body) (build-call (make-preinfo-call) (build-lambda ids body) exps)]))
 
     (define build-named-let
       (lambda (name ids exps body)
-        `(call ,(make-preinfo)
+        `(call ,(make-preinfo-call)
            (letrec ([,name ,(build-lambda ids body)])
              (ref #f ,name))
            ,exps ...)))
@@ -4106,7 +4106,7 @@
                                                  ,(map (lambda (x)
                                                          (build-primcall 3 'car (list (build-ref x))))
                                                     ls*) ...)
-                                              `(call ,(make-preinfo) (ref #f ,do) (ref #f ,r)
+                                              `(call ,(make-preinfo-call) (ref #f ,do) (ref #f ,r)
                                                  ,(map (lambda (x)
                                                          (build-primcall 3 'cdr (list (build-ref x))))
                                                     (cdr ls*)) ...)))))))))
@@ -4229,7 +4229,7 @@
                                                        (build-primcall 3 'vector-ref
                                                          (list (build-ref x) (build-ref i))))
                                                   (cons v v*)) ...)
-                                            `(call ,(make-preinfo) (ref #f ,do) (ref #f ,j))))))))))
+                                            `(call ,(make-preinfo-call) (ref #f ,do) (ref #f ,j))))))))))
                     ctxt empty-env sc wd name moi))])])
 
       (define-inline 3 string-for-each ; should combine with vector-for-each
@@ -4304,7 +4304,7 @@
                                                        (build-primcall 3 'string-ref
                                                          (list (build-ref x) (build-ref i))))
                                                   (cons s s*)) ...)
-                                            `(call ,(make-preinfo) (ref #f ,do) (ref #f ,j))))))))))
+                                            `(call ,(make-preinfo-call) (ref #f ,do) (ref #f ,j))))))))))
                     ctxt empty-env sc wd name moi))])])
 
       (define-inline 3 fold-right
@@ -4349,7 +4349,7 @@
                                            (ref #f ,acc)
                                            ,(map build-ref carls*)
                                            ...)
-                                         (call ,(make-preinfo) (ref #f ,do)
+                                         (call ,(make-preinfo-call) (ref #f ,do)
                                            (call ,(app-preinfo ctxt) (ref #f ,p)
                                              (ref #f ,acc)
                                              ,(map build-ref carls*)
@@ -4396,7 +4396,7 @@
                                                        (build-primcall 3 'car
                                                          (list (build-ref x))))
                                                   ls*) ...)
-                                             (call ,(make-preinfo) (ref #f ,do) (ref #f ,r)
+                                             (call ,(make-preinfo-call) (ref #f ,do) (ref #f ,r)
                                                ,(map (lambda (x)
                                                        (build-primcall 3 'cdr
                                                          (list (build-ref x))))
@@ -4445,7 +4445,7 @@
                                                         ls*) ...))
                                             `(if (ref #f ,t)
                                                  (ref #f ,t)
-                                                 (call ,(make-preinfo) (ref #f ,do) (ref #f ,r)
+                                                 (call ,(make-preinfo-call) (ref #f ,do) (ref #f ,r)
                                                    ,(map (lambda (x)
                                                            (build-primcall 3 'cdr
                                                              (list (build-ref x))))
@@ -4596,11 +4596,11 @@
                            (let ([orig-x (cp0-make-temp #f)] [p (cp0-make-temp #t)])
                              (build-lambda (list orig-x p)
                                (maybe-add-procedure-check ?p level "make-parameter" p
-                                 (build-let (list x) (list `(call ,(make-preinfo) (ref #f ,p) (ref #f ,orig-x)))
+                                 (build-let (list x) (list `(call ,(make-preinfo-call) (ref #f ,p) (ref #f ,orig-x)))
                                    (build-case-lambda (preinfo-call->preinfo-lambda (app-preinfo ctxt))
                                      (list
                                        (list '() (build-ref x))
-                                       (list (list v) `(set! #f ,x (call ,(make-preinfo) (ref #f ,p) (ref #f ,v))))))))))
+                                       (list (list v) `(set! #f ,x (call ,(make-preinfo-call) (ref #f ,p) (ref #f ,v))))))))))
                            (build-lambda (list x)
                              (build-case-lambda (preinfo-call->preinfo-lambda (app-preinfo ctxt))
                                (list
@@ -4639,11 +4639,11 @@
                                  (maybe-add-procedure-check ?p level "make-thread-parameter" p
                                    (build-let (list x)
                                      (list (build-primcall 3 '$allocate-thread-parameter
-                                             (list `(call ,(make-preinfo) (ref #f ,p) (ref #f ,orig-x)))))
+                                             (list `(call ,(make-preinfo-call) (ref #f ,p) (ref #f ,orig-x)))))
                                      (build-case-lambda (preinfo-call->preinfo-lambda (app-preinfo ctxt))
                                        (list
                                          (list '() (mtp-ref x))
-                                         (list (list v) (mtp-set x `(call ,(make-preinfo) (ref #f ,p) (ref #f ,v))))))))))
+                                         (list (list v) (mtp-set x `(call ,(make-preinfo-call) (ref #f ,p) (ref #f ,v))))))))))
                              (build-lambda (list orig-x)
                                (build-let (list x)
                                  (list (build-primcall 3 '$allocate-thread-parameter
@@ -4829,6 +4829,11 @@
        ;; it cleans up and normalizes output, which is at least helpful
        ;; for testing
        (cp0 `(seq ,e1 (call ,preinfo ,pr ,e2)) ctxt env sc wd name moi)]
+      [(call ,preinfo ,pr ,e ,e* ...)
+       (guard (eq? (primref-name pr) '$app))
+       (let ([preinfo (make-preinfo-call (preinfo-src preinfo) (preinfo-sexpr preinfo)
+                                         (not (all-set? (prim-mask unsafe) (primref-flags pr))))])
+         (cp0 `(call ,preinfo ,e ,e* ...) ctxt env sc wd name moi))]
       [(call ,preinfo ,e ,e* ...)
        (let ()
          (define lift-let
diff --git a/s/cpcheck.ss b/s/cpcheck.ss
index 1ed58cf14a..5c8341a867 100644
--- a/s/cpcheck.ss
+++ b/s/cpcheck.ss
@@ -169,10 +169,10 @@
             ,(Expr body ctxt)))]
       [,pr (let ([arity (primref-arity pr)]) (when arity (check! ctxt arity))) pr]
       [(record-ref ,rtd ,type ,index ,[e #f -> e])
-       `(call ,(make-preinfo) ,(lookup-primref 3 '$object-ref)
+       `(call ,(make-preinfo-call) ,(lookup-primref 3 '$object-ref)
           (quote ,type) ,e (quote ,(record-field-offset rtd index)))]
       [(record-set! ,rtd ,type ,index ,[e1 #f -> e1] ,[e2 #f -> e2])
-       `(call ,(make-preinfo) ,(lookup-primref 3 '$object-set!)
+       `(call ,(make-preinfo-call) ,(lookup-primref 3 '$object-set!)
           (quote ,type) ,e1 (quote ,(record-field-offset rtd index)) ,e2)]
       [(record ,rtd ,[rtd-expr #f -> rtd-expr] ,[e* #f -> e*] ...)
        (let ([rtd (maybe-remake-rtd rtd)])
@@ -184,19 +184,19 @@
                                 (if (eq? (filter-foreign-type type) 'scheme-object)
                                     filler*
                                     (cons
-                                      `(call ,(make-preinfo) ,(lookup-primref 3 '$object-set!)
+                                      `(call ,(make-preinfo-call) ,(lookup-primref 3 '$object-set!)
                                          (quote ,type) (ref #f ,rec-t) (quote ,(fld-byte fld)) ,e)
                                       filler*))))
                             '() fld* e*)])
              (if (null? filler*)
-                 `(call ,(make-preinfo) ,(lookup-primref 3 '$record) ,rtd-expr ,e* ...)
+                 `(call ,(make-preinfo-call) ,(lookup-primref 3 '$record) ,rtd-expr ,e* ...)
                  (begin
                    (set-prelex-referenced! rec-t #t)
                    (set-prelex-multiply-referenced! rec-t #t)
-                   `(call ,(make-preinfo)
+                   `(call ,(make-preinfo-call)
                       (case-lambda ,(make-preinfo-lambda)
                         (clause (,rec-t) 1 ,(build-sequence filler* `(ref #f ,rec-t))))
-                      (call ,(make-preinfo) ,(lookup-primref 3 '$record) ,rtd-expr
+                      (call ,(make-preinfo-call) ,(lookup-primref 3 '$record) ,rtd-expr
                         ,(map (lambda (arg) (cond [(eqv? arg 0) `(quote 0)] [else arg]))
                            (make-record-call-args fld* (rtd-size rtd) e*))
                         ...)))))))]
diff --git a/s/cpcommonize.ss b/s/cpcommonize.ss
index 12f44e615f..3661020065 100644
--- a/s/cpcommonize.ss
+++ b/s/cpcommonize.ss
@@ -547,7 +547,7 @@
                              (nanopass-case (Lcommonize1 Expr) (binding-e helper-b)
                                [(case-lambda ,preinfo (clause (,x* ...) ,interface ,body))
                                 (loop (binding-helper-b helper-b) (map (propagate (map cons x* e*)) (map Arg (binding-helper-arg* helper-b))))])
-                             `(call ,(make-preinfo)
+                             `(call ,(make-preinfo-call)
                                 ,(let ([t (binding-x helper-b)])
                                    (if (prelex-referenced t)
                                        (set-prelex-multiply-referenced! t #t)
diff --git a/s/cpletrec.ss b/s/cpletrec.ss
index 3dc856d276..b158e48355 100644
--- a/s/cpletrec.ss
+++ b/s/cpletrec.ss
@@ -141,7 +141,7 @@ Handling letrec and letrec*
             ;; can be removed by other compiler passes if the argument obviously produces
             ;; a single value.
             (fold-right (lambda (e body)
-                          (let ([e (if pure? e `(call ,(make-preinfo) ,(lookup-primref 3 '$value) ,e))])
+                          (let ([e (if pure? e `(call ,(make-preinfo-call) ,(lookup-primref 3 '$value) ,e))])
                             `(seq ,e ,body)))
                         body e*)))
         (define build-let
@@ -232,7 +232,7 @@ Handling letrec and letrec*
                                               (cons lhs lhs*)
                                               lhs*)))
                             '() cb*)])
-              (build-let (make-preinfo) (make-preinfo-lambda) rclhs* (map (lambda (x) `(quote ,(void))) rclhs*)
+              (build-let (make-preinfo-call) (make-preinfo-lambda) rclhs* (map (lambda (x) `(quote ,(void))) rclhs*)
                 (build-letrec (map binding-lhs lb*) (map binding-rhs lb*)
                   (fold-right (lambda (b body)
                                 (let ([lhs (binding-lhs b)] [rhs (binding-rhs b)])
@@ -262,7 +262,7 @@ Handling letrec and letrec*
                     [(and (not (prelex-assigned lhs)) (lambda? rhs))
                      (build-letrec (list lhs) (list rhs) body)]
                     [(not (memq b (node-link* b)))
-                     (build-let (make-preinfo) (make-preinfo-lambda) (list lhs) (list rhs) body)]
+                     (build-let (make-preinfo-call) (make-preinfo-lambda) (list lhs) (list rhs) body)]
                     [else (grisly-letrec '() b* body)]))
                 (let-values ([(lb* cb*) (partition
                                           (lambda (b)
diff --git a/s/cpnanopass.ss b/s/cpnanopass.ss
index ba5f73dda0..0ed3e92716 100644
--- a/s/cpnanopass.ss
+++ b/s/cpnanopass.ss
@@ -1051,7 +1051,8 @@
            (let ([e* (map CaseLambdaExpr e* uvar*)])
              `(letrec ([,uvar* ,e*] ...) ,(Expr body))))]
         [(call ,preinfo ,e ,[e*] ...)
-         `(call ,(make-info-call (preinfo-src preinfo) (preinfo-sexpr preinfo) (fx< (optimize-level) 3) #f #f)
+         (unless (preinfo-call? preinfo) (error 'preinfo-call "oops"))
+         `(call ,(make-info-call (preinfo-src preinfo) (preinfo-sexpr preinfo) (preinfo-call-check? preinfo) #f #f)
             ,(Expr e) ,e* ...)]
         [(foreign (,conv* ...) ,name ,[e] (,arg-type* ...) ,result-type)
          (let ([info (make-info-foreign conv* arg-type* result-type)])
diff --git a/s/cprep.ss b/s/cprep.ss
index dec8664e52..ec0a752dc0 100644
--- a/s/cprep.ss
+++ b/s/cprep.ss
@@ -157,7 +157,13 @@
                [(call ,preinfo ,e ,e* ...)
                 (cache-sexpr preinfo
                   (lambda ()
-                    `(,(uncprep e) ,@(map uncprep e*))))]
+                    (let ([a `(,(uncprep e) ,@(map uncprep e*))])
+                      (if (or (preinfo-call-check? preinfo)
+                              ;; Reporting `#3%$app` is redundant for unsafe mode.
+                              ;; Note that we're losing explicit `#2%$app`s.
+                              (>= (optimize-level) 3))
+                          a
+                          (cons '#3%$app a)))))]
                [,pr (let ([sym (primref-name pr)])
                       (if sexpr?
                           ($sgetprop sym '*unprefixed* sym)
diff --git a/s/cpvalid.ss b/s/cpvalid.ss
index 4602814814..adc68c337e 100644
--- a/s/cpvalid.ss
+++ b/s/cpvalid.ss
@@ -32,7 +32,7 @@
           (lambda (ids vals body)
             (if (null? ids)
                 body
-                `(call ,(make-preinfo)
+                `(call ,(make-preinfo-call)
                    (case-lambda ,(make-preinfo-lambda)
                      (clause (,ids ...) ,(length ids) ,body))
                    ,vals ...))))
@@ -205,7 +205,7 @@
                           `(seq
                              (if (ref #f ,valid-flag)
                                  (quote ,(void))
-                                 (call ,(make-preinfo) ,(lookup-primref 2 '$source-violation)
+                                 (call ,(make-preinfo-call) ,(lookup-primref 2 '$source-violation)
                                    (quote #f)
                                    (quote ,maybe-src)
                                    (quote #t)
diff --git a/s/interpret.ss b/s/interpret.ss
index 5aa4a02009..9768616121 100644
--- a/s/interpret.ss
+++ b/s/interpret.ss
@@ -95,7 +95,7 @@
             (lambda (ids vals body)
               (if (null? ids)
                   body
-                  `(call ,(make-preinfo)
+                  `(call ,(make-preinfo-call)
                      (case-lambda ,(make-preinfo-lambda)
                        (clause (,ids ...) ,(length ids) ,body))
                      ,vals ...))))
diff --git a/s/np-languages.ss b/s/np-languages.ss
index 4e4ef290e6..fbcd3a8a58 100644
--- a/s/np-languages.ss
+++ b/s/np-languages.ss
@@ -73,6 +73,7 @@
     Lsrc Lsrc? Ltype Ltype? unparse-Ltype unparse-Lsrc
     lookup-primref primref? primref-level primref-name primref-flags primref-arity
     preinfo-src preinfo-sexpr preinfo-lambda-name preinfo-lambda-flags preinfo-lambda-libspec
+    preinfo-call? preinfo-call-check?
     prelex-name prelex-name-set!)
 
   (import (nanopass))
diff --git a/s/primdata.ss b/s/primdata.ss
index 91c9e57e05..3b4380f2da 100644
--- a/s/primdata.ss
+++ b/s/primdata.ss
@@ -1756,6 +1756,7 @@
   ($address-in-heap? [flags])
   ($address->object [flags])
   ($allocate-thread-parameter [feature pthreads] [flags alloc])
+  ($app [flags])
   ($apply [flags])
   ($assembly-output [flags])
   ($as-time-goes-by [flags])
diff --git a/s/prims.ss b/s/prims.ss
index 409fe01e6b..a1f67d5994 100644
--- a/s/prims.ss
+++ b/s/prims.ss
@@ -357,6 +357,13 @@
 ;; the argument expression definitely produces a single value.
 (define $value (lambda (x) x))
 
+;; Intended mainly for use as `#3%$app` to indicate that no check
+;; is needed to ensure that the first argument is a function, as
+;; recognized in cp0.
+(define $app
+  (lambda (f . args)
+    (#2%apply f args)))
+
 (define call-with-values
   (lambda (producer consumer)
     (unless (procedure? producer)
diff --git a/s/syntax.ss b/s/syntax.ss
index b39dfffd68..bc7251a1fc 100644
--- a/s/syntax.ss
+++ b/s/syntax.ss
@@ -550,7 +550,7 @@
 (define build-call
   (lambda (ae e e*)
     (build-profile ae
-      `(call ,(make-preinfo (ae->src ae) #f) ,e ,e* ...))))
+      `(call ,(make-preinfo-call (ae->src ae) #f (fx< (optimize-level) 3)) ,e ,e* ...))))
 
 (define build-application
   ; used by chi-application.  pulls profile form off e if e is a lambda expression