diff --git a/collects/ffi/unsafe.rkt b/collects/ffi/unsafe.rkt
index ea0f9e314c..2957c0ff11 100644
--- a/collects/ffi/unsafe.rkt
+++ b/collects/ffi/unsafe.rkt
@@ -933,7 +933,7 @@
     [(_ i  t  ) (type: _pointer
                  pre:  (x => (list->cblock x t)))]
     [(_ o  t n) (type: _pointer
-                 pre:  (if (zero? n) #f (malloc n t))
+                 pre:  (malloc n t)
                  post: (x => (cblock->list x t n)))]
     [(_ io t n) (type: _pointer
                  pre:  (x => (list->cblock x t))
@@ -947,7 +947,7 @@
     [(_ i  t  ) (type: _pointer
                  pre:  (x => (vector->cblock x t)))]
     [(_ o  t n) (type: _pointer
-                 pre:  (if (zero? n) #f (malloc n t))
+                 pre:  (malloc n t)
                  post: (x => (cblock->vector x t n)))]
     [(_ io t n) (type: _pointer
                  pre:  (x => (vector->cblock x t))
diff --git a/collects/scribblings/foreign/pointers.scrbl b/collects/scribblings/foreign/pointers.scrbl
index dfa21e687f..1deb079222 100644
--- a/collects/scribblings/foreign/pointers.scrbl
+++ b/collects/scribblings/foreign/pointers.scrbl
@@ -217,8 +217,11 @@ can contain other information).}
 For general information on C-level memory management with Racket,
 see @|InsideRacket|.
 
-@defproc[(malloc [bytes-or-type (or/c exact-nonnegative-integer? ctype?)]
-                 [type-or-bytes (or/c exact-nonnegative-integer? ctype?) @#,elem{absent}]
+@defproc[(malloc [bytes-or-type (or/c (and/c exact-nonnegative-integer? fixnum?) 
+                                      ctype?)]
+                 [type-or-bytes (or/c (and/c exact-nonnegative-integer? fixnum?) 
+                                      ctype?) 
+                                @#,elem{absent}]
                  [cptr cpointer? @#,elem{absent}]
                  [mode (one-of/c 'nonatomic 'stubborn 'uncollectable
                                  'eternal 'interior 'atomic-interior
@@ -229,8 +232,9 @@ see @|InsideRacket|.
 
 Allocates a memory block of a specified size using a specified
 allocation. The result is a @racket[cpointer] to the allocated
-memory.  Although not reflected above, the four arguments can appear in
-any order since they are all different types of Racket objects; a size
+memory, or @racket[#f] if the requested size is zero.  Although 
+not reflected above, the four arguments can appear in
+any order, since they are all different types of Racket objects; a size
 specification is required at minimum:
 
 @itemize[
diff --git a/collects/tests/racket/foreign-test.rktl b/collects/tests/racket/foreign-test.rktl
index 942709094c..f2279b02a8 100644
--- a/collects/tests/racket/foreign-test.rktl
+++ b/collects/tests/racket/foreign-test.rktl
@@ -6,6 +6,10 @@
 (require mzlib/foreign)
 (unsafe!)
 
+(test #f malloc 0)
+(test #f malloc 0 _int)
+(test #f malloc _int 0)
+
 (let ([big/little (if (system-big-endian?) (lambda (x y) x) (lambda (x y) y))]
       [p (malloc _int32)])
   (ptr-set! p _int32 0)
@@ -168,18 +172,20 @@
         ((ffi 'hoho (_fun _int (_fun _int -> (_fun _int -> _int)) -> _int))
          3 (lambda (x) (lambda (y) (+ y (* x x))))))
   ;; ---
-  (test '(0 1 2 3 4 5 6 7 8 9)
-        'qsort
-        ((get-ffi-obj 'qsort #f
-                      (_fun (l    : (_list io _int len))
-                            (len  : _int = (length l))
-                            (size : _int = (ctype-sizeof _int))
-                            (compare : (_fun _pointer _pointer -> _int))
-                            -> _void -> l))
-         '(7 1 2 3 5 6 4 8 0 9)
-         (lambda (x y)
-           (let ([x (ptr-ref x _int)] [y (ptr-ref y _int)])
-             (cond [(< x y) -1] [(> x y) +1] [else 0])))))
+  (let ([qsort (get-ffi-obj 'qsort #f
+                            (_fun (l    : (_list io _int len))
+                                  (len  : _int = (length l))
+                                  (size : _int = (ctype-sizeof _int))
+                                  (compare : (_fun _pointer _pointer -> _int))
+                                  -> _void -> l))])
+    (test '(0 1 2 3 4 5 6 7 8 9)
+          'qsort
+          (qsort
+           '(7 1 2 3 5 6 4 8 0 9)
+           (lambda (x y)
+             (let ([x (ptr-ref x _int)] [y (ptr-ref y _int)])
+               (cond [(< x y) -1] [(> x y) +1] [else 0])))))
+    (test '() 'qsort (qsort '() (lambda (x y) (error "bad!")))))
   ;; ---
   ;; test vectors
   (t 55 'grab7th (_fun _pointer -> _int ) #"012345678")
diff --git a/src/foreign/foreign.c b/src/foreign/foreign.c
index 0a198a94fd..109982fa5f 100644
--- a/src/foreign/foreign.c
+++ b/src/foreign/foreign.c
@@ -2130,7 +2130,7 @@ static Scheme_Object *fail_ok_sym;
 static Scheme_Object *foreign_malloc(int argc, Scheme_Object *argv[])
 {
   int i, failok=0;
-  intptr_t size=0, num=0;
+  intptr_t size=0, num=-1;
   void *from = NULL, *res = NULL;
   intptr_t foff = 0;
   Scheme_Object *mode = NULL, *a, *base = NULL;
@@ -2139,11 +2139,11 @@ static Scheme_Object *foreign_malloc(int argc, Scheme_Object *argv[])
     a = argv[i];
     a = unwrap_cpointer_property(argv[i]);
     if (SCHEME_INTP(a)) {
-      if (num != 0)
+      if (num != -1)
         scheme_signal_error(MYNAME": specifying a second integer size: %V", a);
       num = SCHEME_INT_VAL(a);
-      if (num <= 0)
-        scheme_wrong_type(MYNAME, "positive fixnum", 0, argc, argv);
+      if (num < 0)
+        scheme_wrong_type(MYNAME, "nonnegative fixnum", 0, argc, argv);
     } else if (SCHEME_CTYPEP(a)) {
       if (size != 0)
         scheme_signal_error(MYNAME": specifying a second type: %V", a);
@@ -2168,8 +2168,9 @@ static Scheme_Object *foreign_malloc(int argc, Scheme_Object *argv[])
       scheme_wrong_type(MYNAME, "malloc-argument", i, argc, argv);
     }
   }
-  if ((num == 0) && (size == 0)) scheme_signal_error(MYNAME": no size given");
-  size = ((size==0) ? 1 : size) * ((num==0) ? 1 : num);
+  if (!num) return scheme_false;
+  if ((num == -1) && (size == 0)) scheme_signal_error(MYNAME": no size given");
+  size = ((size==0) ? 1 : size) * ((num==-1) ? 1 : num);
   if (mode == NULL)
     mf = (base != NULL && CTYPE_PRIMTYPE(base) == &ffi_type_gcpointer)
       ? scheme_malloc : scheme_malloc_atomic;
diff --git a/src/foreign/foreign.rktc b/src/foreign/foreign.rktc
index bf1d8ab50d..f91b3a9222 100755
--- a/src/foreign/foreign.rktc
+++ b/src/foreign/foreign.rktc
@@ -1548,7 +1548,7 @@ static void* SCHEME2C(Scheme_Object *type, void *dst, intptr_t delta,
  * when the type is any pointer, otherwise scheme_malloc_atomic is used. */
 @cdefine[malloc 1 5]{
   int i, failok=0;
-  intptr_t size=0, num=0;
+  intptr_t size=0, num=-1;
   void *from = NULL, *res = NULL;
   intptr_t foff = 0;
   Scheme_Object *mode = NULL, *a, *base = NULL;
@@ -1557,11 +1557,11 @@ static void* SCHEME2C(Scheme_Object *type, void *dst, intptr_t delta,
     a = argv[i];
     a = unwrap_cpointer_property(argv[i]);
     if (SCHEME_INTP(a)) {
-      if (num != 0)
+      if (num != -1)
         scheme_signal_error(MYNAME": specifying a second integer size: %V", a);
       num = SCHEME_INT_VAL(a);
-      if (num <= 0)
-        scheme_wrong_type(MYNAME, "positive fixnum", 0, argc, argv);
+      if (num < 0)
+        scheme_wrong_type(MYNAME, "nonnegative fixnum", 0, argc, argv);
     } else if (SCHEME_CTYPEP(a)) {
       if (size != 0)
         scheme_signal_error(MYNAME": specifying a second type: %V", a);
@@ -1586,8 +1586,9 @@ static void* SCHEME2C(Scheme_Object *type, void *dst, intptr_t delta,
       scheme_wrong_type(MYNAME, "malloc-argument", i, argc, argv);
     }
   }
-  if ((num == 0) && (size == 0)) scheme_signal_error(MYNAME": no size given");
-  size = ((size==0) ? 1 : size) * ((num==0) ? 1 : num);
+  if (!num) return scheme_false;
+  if ((num == -1) && (size == 0)) scheme_signal_error(MYNAME": no size given");
+  size = ((size==0) ? 1 : size) * ((num==-1) ? 1 : num);
   if (mode == NULL)
     mf = (base != NULL && CTYPE_PRIMTYPE(base) == &ffi_type_gcpointer)
       ? scheme_malloc : scheme_malloc_atomic;