diff --git a/src/LinearMath/btScalar.h b/src/LinearMath/btScalar.h
index 00754567b..b101d7416 100644
--- a/src/LinearMath/btScalar.h
+++ b/src/LinearMath/btScalar.h
@@ -49,7 +49,7 @@ inline int	btGetVersion()
 			#define ATTRIBUTE_ALIGNED16(a) a
 			#define ATTRIBUTE_ALIGNED64(a) a
 			#define ATTRIBUTE_ALIGNED128(a) a
-		#elif (_M_ARM)
+		#elif defined(_M_ARM)
 			#define SIMD_FORCE_INLINE __forceinline
 			#define ATTRIBUTE_ALIGNED16(a) __declspec() a
 			#define ATTRIBUTE_ALIGNED64(a) __declspec() a