diff --git a/libavutil/mem.h b/libavutil/mem.h
index e0f17d78bb..09159f7ee8 100644
--- a/libavutil/mem.h
+++ b/libavutil/mem.h
@@ -29,10 +29,10 @@
 #ifdef __ICC
   #define DECLARE_ALIGNED(n,t,v)       t v __attribute__ ((aligned (n)))
   #define DECLARE_ASM_CONST(n,t,v)     const t __attribute__ ((aligned (n))) v
-#elif __GNUC__
+#elif defined(__GNUC__)
   #define DECLARE_ALIGNED(n,t,v)       t v __attribute__ ((aligned (n)))
   #define DECLARE_ASM_CONST(n,t,v)     static const t v attribute_used __attribute__ ((aligned (n)))
-#elif _MSVC
+#elif defined(_MSVC)
   #define DECLARE_ALIGNED(n,t,v)      __declspec(align(n)) t v
   #define DECLARE_ASM_CONST(n,t,v)    __declspec(align(n)) static const t v
 #else