diff --git a/collects/mzlib/foreign.ss b/collects/mzlib/foreign.ss
index a01579b..42a9103 100644
--- a/collects/mzlib/foreign.ss
+++ b/collects/mzlib/foreign.ss
@@ -62,7 +62,7 @@
           _void _int8 _uint8 _int16 _uint16 _int32 _uint32 _int64 _uint64
           _fixint _ufixint _fixnum _ufixnum
           _float _double _double*
-          _bool _pointer _scheme _fpointer
+          _bool _pointer _scheme _fpointer function-ptr
           (unsafe memcpy) (unsafe memmove) (unsafe memset)
           (unsafe malloc-immobile-cell) (unsafe free-immobile-cell))
 
@@ -676,6 +676,13 @@
   (syntax-case stx ()
     [(_ x ...) (begin (set! xs (syntax->list #'(x ...))) (do-fun))]))
 
+(define (function-ptr p fun-ctype)
+  (if (cpointer? p)
+      (if (eq? (ctype->layout fun-ctype) 'fpointer)
+          ((ctype-c->scheme fun-ctype) p)
+          (raise-type-error 'function-ptr "function ctype" fun-ctype))
+      (raise-type-error 'function-ptr "cpointer" p)))
+
 ;; ----------------------------------------------------------------------------
 ;; String types