diff --git a/collects/tests/racket/struct.rktl b/collects/tests/racket/struct.rktl
index 43114766da..7de5306977 100644
--- a/collects/tests/racket/struct.rktl
+++ b/collects/tests/racket/struct.rktl
@@ -1071,6 +1071,31 @@
 (test #f prefab-key? '#(apple))
 (test #t prefab-key? '(apple 4))
 
+;; ----------------------------------------
+;; We can make a bogus mutator, but we can't apply it:
+
+(let ()
+  ;; Test based on code from dmarshall:
+  (define-values (struct:thing make-thing thing? thing-ref thing-set!)
+    (make-struct-type
+     'thing #f 1 0  
+     #f               ; auto val
+     (list)           ; property list
+     #f               ; inspector
+     #f               ; proc-spec
+     (list 0)))       ; immutables
+  
+  (define thing.id  (make-struct-field-accessor thing-ref 0))
+  (define thing.id! (make-struct-field-mutator thing-set! 0))
+
+  (test #t struct-mutator-procedure? thing.id!)
+  (err/rt-test (thing.id!  'new-val))
+  
+  (let ([f #f])
+    ;; defeat inlining to ensure that thunk is JITted:
+    (set! f (lambda () (thing.id! (make-thing 1) 'new-val)))
+    (err/rt-test (f))))
+
 ;; ----------------------------------------
 
 (report-errs)
diff --git a/src/racket/include/scheme.h b/src/racket/include/scheme.h
index b9d894c150..49b27109b7 100644
--- a/src/racket/include/scheme.h
+++ b/src/racket/include/scheme.h
@@ -681,6 +681,7 @@ typedef struct Scheme_Offset_Cptr
 #define SCHEME_PRIM_STRUCT_TYPE_CONSTR           128
 #define SCHEME_PRIM_STRUCT_TYPE_INDEXLESS_SETTER 256
 #define SCHEME_PRIM_STRUCT_TYPE_INDEXED_SETTER   (128 | 256)
+#define SCHEME_PRIM_STRUCT_TYPE_BROKEN_INDEXED_SETTER   (32 | 128)
 #define SCHEME_PRIM_TYPE_PARAMETER               64
 #define SCHEME_PRIM_TYPE_STRUCT_PROP_GETTER      (64 | 128)
 #define SCHEME_PRIM_SOMETIMES_INLINED            (64 | 256)
diff --git a/src/racket/src/print.c b/src/racket/src/print.c
index 2bc0916a4a..252d5085e8 100644
--- a/src/racket/src/print.c
+++ b/src/racket/src/print.c
@@ -2591,6 +2591,7 @@ print(Scheme_Object *obj, int notdisplay, int compact, Scheme_Hash_Table *ht,
             || (kind == SCHEME_PRIM_STRUCT_TYPE_CONSTR)
             || (kind == SCHEME_PRIM_STRUCT_TYPE_INDEXLESS_SETTER)
             || (kind == SCHEME_PRIM_STRUCT_TYPE_INDEXED_SETTER)
+            || (kind == SCHEME_PRIM_STRUCT_TYPE_BROKEN_INDEXED_SETTER)
             || (kind == SCHEME_PRIM_STRUCT_TYPE_INDEXED_GETTER)
             || (kind == SCHEME_PRIM_STRUCT_TYPE_PRED)) {
 	  print_named(obj, "struct-procedure", 
diff --git a/src/racket/src/struct.c b/src/racket/src/struct.c
index b254819d1d..fa8820983c 100644
--- a/src/racket/src/struct.c
+++ b/src/racket/src/struct.c
@@ -1325,7 +1325,7 @@ static Scheme_Object *guard_property(Scheme_Object *prop, Scheme_Object *v, Sche
     if (SCHEME_INTP(v)) {
       intptr_t pos;
       pos = SCHEME_INT_VAL(orig_v);
-      if (!t->immutables || !t->immutables[pos]) {
+      if (!t->immutables || !t->immutables[pos]) { 
         scheme_contract_error("make-struct-type", 
                               "field is not specified as immutable for a prop:procedure index", 
                               "index", 1, orig_v,
@@ -3040,7 +3040,8 @@ struct_setter_p(int argc, Scheme_Object *argv[])
   Scheme_Object *v = argv[0];
   if (SCHEME_CHAPERONEP(v)) v = SCHEME_CHAPERONE_VAL(v);
   return ((STRUCT_mPROCP(v, SCHEME_PRIM_STRUCT_TYPE_INDEXED_SETTER)
-	   || STRUCT_mPROCP(v, SCHEME_PRIM_STRUCT_TYPE_INDEXLESS_SETTER))
+	   || STRUCT_mPROCP(v, SCHEME_PRIM_STRUCT_TYPE_INDEXLESS_SETTER)
+           || STRUCT_mPROCP(v, SCHEME_PRIM_STRUCT_TYPE_BROKEN_INDEXED_SETTER))
 	  ? scheme_true : scheme_false);
 }
 
@@ -3827,6 +3828,8 @@ make_struct_proc(Scheme_Struct_Type *struct_type,
 					   2 + need_pos, 2 + need_pos, 0);
       if (need_pos)
 	flags |= SCHEME_PRIM_STRUCT_TYPE_INDEXLESS_SETTER;
+      else if (struct_type->immutables && struct_type->immutables[field_num])
+	flags |= SCHEME_PRIM_STRUCT_TYPE_BROKEN_INDEXED_SETTER;
       else
 	flags |= SCHEME_PRIM_STRUCT_TYPE_INDEXED_SETTER;
       /* See note above:
@@ -3844,7 +3847,8 @@ Scheme_Object *scheme_rename_struct_proc(Scheme_Object *p, Scheme_Object *sym)
   if (SCHEME_PRIMP(p)) {
     unsigned short flags = ((Scheme_Primitive_Proc *)p)->pp.flags;
     int is_getter = ((flags & SCHEME_PRIM_OTHER_TYPE_MASK) == SCHEME_PRIM_STRUCT_TYPE_INDEXED_GETTER);
-    int is_setter = ((flags & SCHEME_PRIM_OTHER_TYPE_MASK) == SCHEME_PRIM_STRUCT_TYPE_INDEXED_SETTER);
+    int is_setter = (((flags & SCHEME_PRIM_OTHER_TYPE_MASK) == SCHEME_PRIM_STRUCT_TYPE_INDEXED_SETTER)
+                     || ((flags & SCHEME_PRIM_OTHER_TYPE_MASK) == SCHEME_PRIM_STRUCT_TYPE_BROKEN_INDEXED_SETTER));
       
     if (is_getter || is_setter) {
       const char *func_name;