diff --git a/public/mathlib/vector.h b/public/mathlib/vector.h
index be644474..5e2a3b91 100644
--- a/public/mathlib/vector.h
+++ b/public/mathlib/vector.h
@@ -237,7 +237,11 @@ private:
 
 
 
-#define USE_M64S ( ( !defined( _X360 ) ) )
+#ifdef _X360
+#define USE_M64S 1
+#else
+#define USE_M64S 0
+#endif