--- a/pthread_attr_getstackaddr.c
+++ b/pthread_attr_getstackaddr.c
@@ -38,7 +38,7 @@
 #include "implement.h"
 
 /* ignore warning "unreferenced formal parameter" */
-#ifdef _MSC_VER
+#if defined(_MSC_VER)
 #pragma warning( disable : 4100 )
 #endif