diff --git a/vm/os-macosx-x86.64.h b/vm/os-macosx-x86.64.h
new file mode 100644
index 0000000000..d2bb48c3fe
--- /dev/null
+++ b/vm/os-macosx-x86.64.h
@@ -0,0 +1,35 @@
+/* Fault handler information.  MacOSX version.
+Copyright (C) 1993-1999, 2002-2003  Bruno Haible <clisp.org at bruno>
+Copyright (C) 2003  Paolo Bonzini <gnu.org at bonzini>
+
+Used under BSD license with permission from Paolo Bonzini and Bruno Haible,
+2005-03-10:
+
+http://sourceforge.net/mailarchive/message.php?msg_name=200503102200.32002.bruno%40clisp.org
+
+Modified for Factor by Slava Pestov and Daniel Ehrenberg */
+#define MACH_EXC_STATE_TYPE x86_exception_state64_t
+#define MACH_EXC_STATE_FLAVOR x86_EXCEPTION_STATE64
+#define MACH_EXC_STATE_COUNT x86_EXCEPTION_STATE64_COUNT
+#define MACH_THREAD_STATE_TYPE x86_thread_state64_t
+#define MACH_THREAD_STATE_FLAVOR x86_THREAD_STATE64
+#define MACH_THREAD_STATE_COUNT MACHINE_THREAD_STATE_COUNT
+
+#if __DARWIN_UNIX03
+	#define MACH_EXC_STATE_FAULT(exc_state) (exc_state)->__faultvaddr
+	#define MACH_STACK_POINTER(thr_state) (thr_state)->__rsp
+	#define MACH_PROGRAM_COUNTER(thr_state) (thr_state)->__rip
+	#define UAP_PROGRAM_COUNTER(ucontext) \
+		MACH_PROGRAM_COUNTER(&(((ucontext_t *)(ucontext))->uc_mcontext->__ss))
+#else
+	#define MACH_EXC_STATE_FAULT(exc_state) (exc_state)->faultvaddr
+	#define MACH_STACK_POINTER(thr_state) (thr_state)->rsp
+	#define MACH_PROGRAM_COUNTER(thr_state) (thr_state)->rip
+	#define UAP_PROGRAM_COUNTER(ucontext) \
+		MACH_PROGRAM_COUNTER(&(((ucontext_t *)(ucontext))->uc_mcontext->ss))	
+#endif
+
+INLINE CELL fix_stack_pointer(CELL sp)
+{
+	return ((sp + 8) & ~15) - 8;
+}