diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index ce0fe17a2..1ece08df3 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -280,7 +280,7 @@ void pgf_write_pgf(const char* fpath,
         fclose(out);
 }
 
-#ifdef _GNU_SOURCE
+#if defined(__linux__)
 PGF_API
 void pgf_write_pgf_cookie
                   (void *cookie, cookie_io_functions_t *io_funcs,
@@ -308,6 +308,35 @@ void pgf_write_pgf_cookie
     if (out != NULL)
         fclose(out);
 }
+#elif defined(__APPLE__)
+PGF_API
+void pgf_write_pgf_cookie
+                  (void *cookie, int (*writefn)(void *, const char *, int),
+                                 int (*closefn)(void *),
+                   PgfDB *db, PgfRevision revision,
+                   PgfText **langs, // null terminated list or null
+                   PgfExn* err)
+{
+    FILE *out = NULL;
+
+    PGF_API_BEGIN {
+        out = funopen(cookie, NULL, writefn, NULL, closefn);
+        if (!out) {
+            throw pgf_systemerror(errno, "<cookie>");
+        }
+
+        {
+            DB_scope scope(db, READER_SCOPE);
+            ref<PgfPGF> pgf = db->revision2pgf(revision);
+
+            PgfWriter wtr(langs, out);
+            wtr.write_pgf(pgf);
+        }
+    } PGF_API_END
+
+    if (out != NULL)
+        fclose(out);
+}
 #endif
 
 PGF_API
diff --git a/src/runtime/c/pgf/pgf.h b/src/runtime/c/pgf/pgf.h
index 70109a2da..502b40862 100644
--- a/src/runtime/c/pgf/pgf.h
+++ b/src/runtime/c/pgf/pgf.h
@@ -291,13 +291,21 @@ void pgf_write_pgf(const char* fpath,
                    PgfText **langs, // null terminated list or null
                    PgfExn* err);
 
-#ifdef _GNU_SOURCE
+#if defined(__linux__)
 PGF_API_DECL
 void pgf_write_pgf_cookie
                   (void *cookie, cookie_io_functions_t *io_funcs,
                    PgfDB *db, PgfRevision revision,
                    PgfText **langs, // null terminated list or null
                    PgfExn* err);
+#elif defined(__APPLE__)
+PGF_API_DECL
+void pgf_write_pgf_cookie
+                  (void *cookie, int (*writefn)(void *, const char *, int),
+                                 int (*closefn)(void *),
+                   PgfDB *db, PgfRevision revision,
+                   PgfText **langs, // null terminated list or null
+                   PgfExn* err);
 #endif
 
 PGF_API_DECL
diff --git a/src/runtime/haskell/PGF2.hsc b/src/runtime/haskell/PGF2.hsc
index 39419d477..cdb3c1e20 100644
--- a/src/runtime/haskell/PGF2.hsc
+++ b/src/runtime/haskell/PGF2.hsc
@@ -208,8 +208,8 @@ writePGF fpath p mb_langs =
     withLangs clangs []           f = withArray0 nullPtr (reverse clangs) f
     withLangs clangs (lang:langs) f = withText lang $ \clang -> withLangs (clang:clangs) langs f
 
-#ifdef __linux__
-writePGF_ :: (Ptr Word8 -> CSize -> IO CSize) -> PGF -> Maybe [ConcName] -> IO ()
+#if defined(__linux__)
+writePGF_ :: (Ptr Word8 -> Int -> IO Int) -> PGF -> Maybe [ConcName] -> IO ()
 writePGF_ callback p mb_langs =
   allocaBytes (#size cookie_io_functions_t) $ \io_functions ->
   withForeignPtr (a_revision p) $ \c_revision ->
@@ -223,12 +223,11 @@ writePGF_ callback p mb_langs =
   where
     withLangs clangs []           f = withArray0 nullPtr (reverse clangs) f
     withLangs clangs (lang:langs) f = withText lang $ \clang -> withLangs (clang:clangs) langs f
-#endif
 
 cookie_write :: Ptr () -> Ptr Word8 -> CSize -> IO CSize
 cookie_write cookie buf size = do
   callback <- deRefStablePtr (castPtrToStablePtr cookie)
-  callback buf size
+  fmap fromIntegral $ (callback :: Ptr Word8 -> Int -> IO Int) buf (fromIntegral size)
 
 foreign export ccall cookie_write :: Ptr () -> Ptr Word8 -> CSize -> IO CSize
 foreign import ccall "&cookie_write" cookie_write_ptr :: FunPtr (Ptr () -> Ptr Word8 -> CSize -> IO CSize)
@@ -241,6 +240,36 @@ cookie_close cookie = do
 foreign export ccall cookie_close :: Ptr () -> IO CInt
 foreign import ccall "&cookie_close" cookie_close_ptr :: FunPtr (Ptr () -> IO CInt)
 
+#elif defined(__APPLE__)
+
+writePGF_ :: (Ptr Word8 -> Int -> IO Int) -> PGF -> Maybe [ConcName] -> IO ()
+writePGF_ callback p mb_langs =
+  withForeignPtr (a_revision p) $ \c_revision ->
+  maybe (\f -> f nullPtr) (withLangs []) mb_langs $ \c_langs -> do
+    cookie <- fmap castStablePtrToPtr (newStablePtr callback)
+    withPgfExn "writePGF_" (pgf_write_pgf_cookie cookie cookie_write_ptr cookie_close_ptr (a_db p) c_revision c_langs)
+  where
+    withLangs clangs []           f = withArray0 nullPtr (reverse clangs) f
+    withLangs clangs (lang:langs) f = withText lang $ \clang -> withLangs (clang:clangs) langs f
+
+cookie_write :: Ptr () -> Ptr Word8 -> CInt -> IO CInt
+cookie_write cookie buf size = do
+  callback <- deRefStablePtr (castPtrToStablePtr cookie)
+  fmap fromIntegral $ (callback :: Ptr Word8 -> Int -> IO Int) buf (fromIntegral size)
+
+foreign export ccall cookie_write :: Ptr () -> Ptr Word8 -> CInt -> IO CInt
+foreign import ccall "&cookie_write" cookie_write_ptr :: FunPtr (Ptr () -> Ptr Word8 -> CInt -> IO CInt)
+
+cookie_close :: Ptr () -> IO CInt
+cookie_close cookie = do
+  freeStablePtr (castPtrToStablePtr cookie)
+  return 0
+
+foreign export ccall cookie_close :: Ptr () -> IO CInt
+foreign import ccall "&cookie_close" cookie_close_ptr 
+
+#endif
+
 showPGF :: PGF -> String
 showPGF p =
   render (text "abstract" <+> ppAbstractName p <+> char '{' $$
diff --git a/src/runtime/haskell/PGF2/FFI.hsc b/src/runtime/haskell/PGF2/FFI.hsc
index 50e93da86..4d0a8db9b 100644
--- a/src/runtime/haskell/PGF2/FFI.hsc
+++ b/src/runtime/haskell/PGF2/FFI.hsc
@@ -56,7 +56,6 @@ data PgfCohortsCallback
 data PgfPhrasetableIds
 data PgfExprEnum
 data PgfAlignmentPhrase
-data CookieIOFunctions
 
 type Wrapper a = a -> IO (FunPtr a)
 type Dynamic a = FunPtr a -> a
@@ -86,8 +85,11 @@ foreign import ccall pgf_merge_pgf :: Ptr PgfDB -> Ptr PGF -> CString -> Ptr Pgf
 
 foreign import ccall pgf_write_pgf :: CString -> Ptr PgfDB -> Ptr PGF -> Ptr (Ptr PgfText) -> Ptr PgfExn -> IO ()
 
-#ifdef _GNU_SOURCE
+#if defined(__linux__)
+data CookieIOFunctions
 foreign import ccall pgf_write_pgf_cookie :: Ptr () -> Ptr CookieIOFunctions -> Ptr PgfDB -> Ptr PGF -> Ptr (Ptr PgfText) -> Ptr PgfExn -> IO ()
+#elif defined(__APPLE__)
+foreign import ccall pgf_write_pgf_cookie :: Ptr () -> FunPtr (Ptr () -> Ptr Word8 -> CInt -> IO CInt) -> FunPtr (Ptr () -> IO CInt) -> Ptr PgfDB -> Ptr PGF -> Ptr (Ptr PgfText) -> Ptr PgfExn -> IO ()
 #endif
 
 foreign import ccall "pgf_free_revision" pgf_free_revision_ :: Ptr PgfDB -> Ptr PGF -> IO ()