--- a/pthread_attr_setscope.c
+++ b/pthread_attr_setscope.c
@@ -38,14 +38,14 @@
 #include "implement.h"
 
 /* ignore warning "unreferenced formal parameter" */
-#ifdef _MSC_VER
+#if defined(_MSC_VER)
 #pragma warning( disable : 4100 )
 #endif
 
 int
 pthread_attr_setscope (pthread_attr_t * attr, int contentionscope)
 {
-#ifdef _POSIX_THREAD_PRIORITY_SCHEDULING
+#if defined(_POSIX_THREAD_PRIORITY_SCHEDULING)
   switch (contentionscope)
     {
     case PTHREAD_SCOPE_SYSTEM: