diff --git a/collects/compiler/zo-marshal.rkt b/collects/compiler/zo-marshal.rkt
index 6e0d8ae475..29bff55b83 100644
--- a/collects/compiler/zo-marshal.rkt
+++ b/collects/compiler/zo-marshal.rkt
@@ -271,6 +271,7 @@
 (define begin0-sequence-type-num 100)
 (define module-type-num 103)
 (define prefix-type-num 105)
+(define free-id-info-type-num 154)
 
 (define-syntax define-enum
   (syntax-rules ()
@@ -446,6 +447,14 @@
                   (list->vector stxs)))
       out)]))
 
+(define (out-free-id-info a-free-id-info out)
+  (match a-free-id-info
+    [(struct free-id-info (mpi0 s0 mpi1 s1 p0 p1 p2 insp?))
+     (out-marshaled
+      free-id-info-type-num
+      (vector mpi0 s0 mpi1 s1 p0 p1 p2 insp?)
+      out)]))
+
 (define-struct module-decl (content))
 
 (define (out-module mod-form out)
@@ -954,6 +963,7 @@
     [(prefix? expr) (out-prefix expr out)]
     [(global-bucket? expr) (out-toplevel expr out)]
     [(module-variable? expr) (out-toplevel expr out)]
+    [(free-id-info? expr) (out-free-id-info expr out)]
     [else (out-form expr out)]))
 
 (define (out-value expr out)
diff --git a/collects/compiler/zo-parse.rkt b/collects/compiler/zo-parse.rkt
index e7adc72a82..3afd74e4d3 100644
--- a/collects/compiler/zo-parse.rkt
+++ b/collects/compiler/zo-parse.rkt
@@ -70,6 +70,11 @@
        ; XXX Why not leave them as vectors and change the contract?
        (make-prefix i (vector->list tv) (vector->list sv))])))
 
+(define read-free-id-info
+  (match-lambda
+    [(vector mpi0 symbol0 mpi1 symbol1 num0 num1 num2 bool0) ; I have no idea what these mean
+     (make-free-id-info mpi0 symbol0 mpi1 symbol1 num0 num1 num2 bool0)]))
+
 (define (read-unclosed-procedure v)
   (define CLOS_HAS_REST 1)
   (define CLOS_HAS_REF_ARGS 2)
@@ -313,6 +318,7 @@
     [(100) 'begin0-sequence-type]
     [(103) 'module-type]
     [(105) 'resolve-prefix-type]
+    [(154) 'free-id-info-type]
     [else (error 'int->type "unknown type: ~e" i)]))
 
 (define type-readers
@@ -333,7 +339,8 @@
     (cons 'case-lambda-sequence-type read-case-lambda)
     (cons 'begin0-sequence-type read-sequence)
     (cons 'module-type read-module)
-    (cons 'resolve-prefix-type read-resolve-prefix))))
+    (cons 'resolve-prefix-type read-resolve-prefix)
+    (cons 'free-id-info-type read-free-id-info))))
 
 (define (get-reader type)
   (or (hash-ref type-readers type #f)
diff --git a/collects/compiler/zo-structs.rkt b/collects/compiler/zo-structs.rkt
index 8cc5042729..509a2dc7d5 100644
--- a/collects/compiler/zo-structs.rkt
+++ b/collects/compiler/zo-structs.rkt
@@ -169,9 +169,27 @@
 ;; Top-level `require'
 (define-form-struct (req form) ([reqs stx?] [dummy toplevel?]))
 
-(define-form-struct (lexical-rename wrap) ([bool1 boolean?] ; this needs a name
+
+(define-form-struct free-id-info ([path0 module-path-index?]
+                                  [symbol0 symbol?]
+                                  [path1 module-path-index?]
+                                  [symbol1 symbol?]
+                                  [phase0 (or/c exact-integer? #f)]
+                                  [phase1 (or/c exact-integer? #f)]
+                                  [phase2 (or/c exact-integer? #f)]
+                                  [use-current-inspector? boolean?]))
+
+(define-form-struct (lexical-rename wrap) ([has-free-id-renames? boolean?]
                                            [bool2 boolean?] ; this needs a name
-                                           [alist any/c])) ; should be (listof (cons/c symbol? symbol?))
+                                           [alist (listof 
+                                                   (cons/c symbol?
+                                                           (or/c
+                                                            symbol?
+                                                            (cons/c
+                                                             symbol?
+                                                             (or/c
+                                                              (cons/c symbol? (or/c symbol? #f))
+                                                              free-id-info?)))))])) 
 (define-form-struct (phase-shift wrap) ([amt exact-integer?] [src (or/c module-path-index? #f)] [dest (or/c module-path-index? #f)]))
 (define-form-struct (wrap-mark wrap) ([val exact-integer?]))
 (define-form-struct (prune wrap) ([sym any/c]))
@@ -179,7 +197,7 @@
 (define-form-struct all-from-module ([path module-path-index?] 
                                      [phase (or/c exact-integer? #f)] 
                                      [src-phase any/c] ; should be (or/c exact-integer? #f)
-                                     [exceptions (or/c (listof symbol?) #f)] ; should be (listof symbol?)
+                                     [exceptions (or/c (listof (or/c symbol? number?)) #f)] ; should be (listof symbol?)
                                      [prefix (or/c (vector/c (or/c symbol? #f)) #f)])) ; should be (or/c symbol? #f)
 
 (define-form-struct nominal-path ())
@@ -226,3 +244,5 @@
 
 
 
+
+