diff --git a/src/CHANGELOG b/src/CHANGELOG
index 3011f1f09..933777408 100644
--- a/src/CHANGELOG
+++ b/src/CHANGELOG
@@ -1,6 +1,11 @@
 ECL 0.9i
 ========
 
+* New platforms:
+
+ - Patches in assembler code and GC headers to build ECL on Mac OSX/Intel
+   contributed by Brad Beveridge.
+
 * Visible changes:
 
  - Many functions have got now the prefix "ecl_" so as to avoid namespace
@@ -88,10 +93,11 @@ ECL 0.9i
    COMPUTE-SLOTS assign a location to each slot definition that has allocation
    :INSTANCE or :CLASS.
 
- - A new defclass option, :optimize-slot-access, which defaults to T, controls
-   whether the slots accessors should address directly the values in the class
-   or use SLOT-VALUE. It should be set to NIL when one intends to redefine the
-   SLOT-*-USING-CLASS methods.
+ - A new defclass option, :OPTIMIZE-SLOT-ACCESS, which defaults to the value of
+   CLOS:*OPTIMIZE-SLOT-ACCESS*, controls whether the slots accessors should
+   address directly the values in the class or use SLOT-VALUE. It should be set
+   to NIL when one intends to redefine the SLOT-*-USING-CLASS methods, and
+   to T when trying to get the most of the speed.
 
  - Implemented [FUNCALLABLE-]STANDARD-INSTANCE-ACCESS. They are synonyms for
    SI:INSTANCE-REF and are, as such, inlined and _very_ unsafe. Use with care.
diff --git a/src/c/arch/ffi_x86.d b/src/c/arch/ffi_x86.d
index 3778b3bdd..ff59f50d8 100644
--- a/src/c/arch/ffi_x86.d
+++ b/src/c/arch/ffi_x86.d
@@ -74,7 +74,9 @@ ecl_fficall_execute(void *f_ptr, struct ecl_fficall *fficall, enum ecl_ffi_tag r
 	"subl	%1, %%esp\n\t"
 	"movl	%2, %%esi\n\t"
 	"movl	%%esp, %%edi\n\t"
-	"rep	movsb\n\t": "=a" (stack_p) : "c" (bufsize), "d" (buf) : "%edi", "%esi");
+	"rep\n\t"
+        "movsb\n\t"
+        : "=a" (stack_p) : "c" (bufsize), "d" (buf) : "%edi", "%esi");
 #endif
 	if (return_type <= ECL_FFI_UNSIGNED_LONG) {
 		fficall->output.i = ((int (*)())f_ptr)();
diff --git a/src/gc/include/private/gcconfig.h b/src/gc/include/private/gcconfig.h
index 9546c206c..344e8949d 100644
--- a/src/gc/include/private/gcconfig.h
+++ b/src/gc/include/private/gcconfig.h
@@ -300,7 +300,7 @@
 #    define mach_type_known
 #   elif defined(__i386__)
 #    define I386
-     --> Not really supported, but at least we recognize it.
+#    define mach_type_known
 #   endif
 # endif
 # if defined(NeXT) && defined(mc68000)
@@ -1278,6 +1278,50 @@
 /* #     define MPROTECT_VDB  Not quite working yet? */
 #     define DYNAMIC_LOADING
 #   endif
+#   ifdef DARWIN
+#   if defined(__LP64__) || defined(_WIN64)
+#     define CPP_WORDSZ 64
+#     define ALIGNMENT 8
+#   else
+#     define CPP_WORDSZ 32
+#     define ALIGNMENT 4
+			/* Appears to hold for all "32 bit" compilers	*/
+			/* except Borland.  The -a4 option fixes 	*/
+			/* Borland.					*/
+                        /* Ivan Demakov: For Watcom the option is -zp4. */
+#   endif
+#     define OS_TYPE "DARWIN"
+#     define DYNAMIC_LOADING
+      /* XXX: see get_end(3), get_etext() and get_end() should not be used.
+         These aren't used when dyld support is enabled (it is by default) */
+#     define DATASTART ((ptr_t) get_etext())
+#     define DATAEND	((ptr_t) get_end())
+#     define STACKBOTTOM ((ptr_t) 0xc0000000)
+#     define USE_MMAP
+#     define USE_MMAP_ANON
+#     define USE_ASM_PUSH_REGS
+      /* This is potentially buggy. It needs more testing. See the comments in
+         os_dep.c.  It relies on threads to track writes. */
+#     ifdef GC_DARWIN_THREADS
+/* #       define MPROTECT_VDB -- diabled for now.  May work for some apps. */
+#     endif
+#     include <unistd.h>
+#     define GETPAGESIZE() getpagesize()
+
+#if 0
+#     if defined(USE_PPC_PREFETCH) && defined(__GNUC__)
+	/* The performance impact of prefetches is untested */
+#	define PREFETCH(x) \
+	  __asm__ __volatile__ ("dcbt 0,%0" : : "r" ((const void *) (x)))
+#	define PREFETCH_FOR_WRITE(x) \
+	  __asm__ __volatile__ ("dcbtst 0,%0" : : "r" ((const void *) (x)))
+#     endif
+#endif
+      /* There seems to be some issues with trylock hanging on darwin. This
+         should be looked into some more */
+#     define NO_PTHREAD_TRYLOCK
+#   endif
+
 # endif
 
 # ifdef NS32K