diff --git a/src/cc_mm.c b/src/cc_mm.c
index ef4ed349a..8fa28f980 100644
--- a/src/cc_mm.c
+++ b/src/cc_mm.c
@@ -24,8 +24,7 @@
 #include <string.h>
 #include <sys/mman.h>
 
-/* TODO(yao): detect OS in one place and use one variable everywhere */
-#if defined(__APPLE__) && defined(__MACH__)
+#ifdef OS_DARWIN
 #   define MAP_ANONYMOUS MAP_ANON
 #include <malloc/malloc.h>
 #define malloc_usable_size malloc_size