diff --git a/library/timing.c b/library/timing.c
index 0f5f4bd..0b62b10 100644
--- a/library/timing.c
+++ b/library/timing.c
@@ -27,7 +27,7 @@
 
 #include "polarssl/timing.h"
 
-#if defined(WIN32)
+#if defined(_WIN32)
 
 #include <windows.h>
 #include <winbase.h>
@@ -164,7 +164,7 @@
 
 int alarmed = 0;
 
-#if defined(WIN32)
+#if defined(_WIN32)
 
 unsigned long get_timer( struct hr_time *val, int reset )
 {