diff --git a/c32 b/c32
index b4b790b..66b5b9e 100755
--- a/c32
+++ b/c32
@@ -2,7 +2,7 @@
 
 ./configure \
   --prefix=$HOME/.opt32 \
-  CFLAGS="-m32 -I$HOME/.opt32/include -I$HOME/.opt32/lib/libffi-3.0.6/include" \
+  CFLAGS="-m32 -I$HOME/.opt32/include -I$HOME/.opt32/lib/libffi-3.0.8/include" \
   LDFLAGS="-m32 -L$HOME/.opt32/lib" \
 && make clean \
 && make
diff --git a/c64 b/c64
index 27b5529..153b180 100755
--- a/c64
+++ b/c64
@@ -1,7 +1,7 @@
 #!/usr/bin/env sh
 
-./configure --prefix=/Users/ikarus/.opt \
-  CFLAGS="-m64 -I $HOME/.opt64/include -I $HOME/.opt64/lib/libffi-3.0.6/include" \
+./configure --prefix=$HOME/.opt64 \
+  CFLAGS="-m64 -I $HOME/.opt64/include -I $HOME/.opt64/lib/libffi-3.0.8/include" \
   LDFLAGS="-m64 -L$HOME/.opt64/lib" \
 && make clean \
 && make
diff --git a/config.h.in b/config.h.in
index 8b81e47..d8683a5 100644
--- a/config.h.in
+++ b/config.h.in
@@ -6,6 +6,11 @@
 /* use flat segment and dirty vectors (not used yet) */
 #undef FLAT_TABLES
 
+/* Mark code returned by libffi executable because libffi does not do that
+   yet. This so far is only important on Snow Leopard in 64-bit mode but we
+   mark it on all darwins anyways. */
+#undef HACK_FFI
+
 /* Define to 1 if you have the <assert.h> header file. */
 #undef HAVE_ASSERT_H
 
@@ -153,9 +158,6 @@
 /* Define to 1 if your C compiler doesn't accept -c and -o together. */
 #undef NO_MINUS_C_MINUS_O
 
-/* Name of package */
-#undef PACKAGE
-
 /* Define to the address where bug reports for this package should be sent. */
 #undef PACKAGE_BUGREPORT
 
@@ -186,9 +188,6 @@
 /* Define to 1 if your <sys/time.h> declares `struct tm'. */
 #undef TM_IN_SYS_TIME
 
-/* Version number of package */
-#undef VERSION
-
 /* Number of bits in a file offset, on hosts where this is settable. */
 #undef _FILE_OFFSET_BITS
 
diff --git a/configure b/configure
index 2ba400d..151fc60 100755
--- a/configure
+++ b/configure
@@ -2996,15 +2996,6 @@ fi
  VERSION=0.0.4-rc1
 
 
-cat >>confdefs.h <<_ACEOF
-#define PACKAGE "$PACKAGE"
-_ACEOF
-
-
-cat >>confdefs.h <<_ACEOF
-#define VERSION "$VERSION"
-_ACEOF
-
 # Some tools Automake needs.
 
 ACLOCAL=${ACLOCAL-"${am_missing_run}aclocal-${am__api_version}"}
@@ -4931,6 +4922,11 @@ case "$target_os" in
     ;;
   *cygwin*)
     LDFLAGS="-Wl,-E -Wl,--export-all-symbols $LDFLAGS"
+    ;;
+  *darwin*)
+
+$as_echo "#define HACK_FFI 1" >>confdefs.h
+
     ;;
   esac
 
diff --git a/configure.ac b/configure.ac
index b99b163..35d75e8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4,7 +4,7 @@
 AC_PREREQ(2.59)
 AC_INIT(ikarus, 0.0.4-rc1, aghuloum@cs.indiana.edu)
 AC_CANONICAL_SYSTEM
-AM_INIT_AUTOMAKE(ikarus, 0.0.4-rc1)
+AM_INIT_AUTOMAKE(ikarus, 0.0.4-rc1, gnu)
 AC_CONFIG_SRCDIR([src/])
 
 
@@ -26,6 +26,13 @@ case "$target_os" in
   *cygwin*)
     LDFLAGS="-Wl,-E -Wl,--export-all-symbols $LDFLAGS"
     ;;
+  *darwin*)
+    AC_DEFINE(HACK_FFI, 1, 
+              [Mark code returned by libffi executable because
+               libffi does not do that yet.  This so far is only
+               important on Snow Leopard in 64-bit mode but we
+               mark it on all darwins anyways.])
+    ;;
   esac
 
 AC_CHECK_SIZEOF(void *)
diff --git a/src/ikarus-ffi.c b/src/ikarus-ffi.c
index ffa94bc..12f1ab7 100644
--- a/src/ikarus-ffi.c
+++ b/src/ikarus-ffi.c
@@ -10,6 +10,10 @@
 
 #undef DEBUG_FFI
 
+#ifdef HACK_FFI
+#include <sys/mman.h>
+#endif
+
 static void*
 alloc(size_t n, int m) {
   void* x = calloc(n, m);
@@ -435,6 +439,20 @@ ikrt_prepare_callback(ikptr data, ikpcb* pcb){
   ikptr cifptr = ref(data, off_vector_data + 0 * wordsize);
   void* codeloc;
   ffi_closure* closure = ffi_closure_alloc(sizeof(ffi_closure), &codeloc);
+
+#ifdef HACK_FFI
+  {
+    long code_start = align_to_prev_page(codeloc);
+    long code_end =
+      align_to_next_page(FFI_TRAMPOLINE_SIZE+(-1)+(long)codeloc);
+    int rv = mprotect((void*)code_start, code_end - code_start,
+        PROT_READ|PROT_WRITE|PROT_EXEC);
+    if(rv) {
+      fprintf(stderr, "Error mprotecting code page!\n");
+    }
+  }
+#endif
+
   ffi_cif* cif = (ffi_cif*) ref(cifptr, off_pointer_data);
   
   callback_locative* loc = malloc(sizeof(callback_locative));