diff --git a/src/libthread/threadimpl.h b/src/libthread/threadimpl.h
index 3d68299..76f676f 100644
--- a/src/libthread/threadimpl.h
+++ b/src/libthread/threadimpl.h
@@ -21,7 +21,7 @@
 extern	void		makecontext(ucontext_t*, void(*)(), int, ...);
 #endif
 
-#if defined(__APPLE__) && !defined(__DARWIN_UNIX03)
+#if defined(__APPLE__) && MAC_OS_X_VERSION_MAX_ALLOWED <= MAC_OS_X_VERSION_10_4
 #	define mcontext libthread_mcontext
 #	define mcontext_t libthread_mcontext_t
 #	define ucontext libthread_ucontext