diff --git a/client/sleep.c b/client/sleep.c
index 6b0717c6..08a656b9 100644
--- a/client/sleep.c
+++ b/client/sleep.c
@@ -8,7 +8,7 @@
 // platform-independant sleep macros
 //-----------------------------------------------------------------------------
 
-#ifndef __WIN32
+#ifndef _WIN32
 
 #define _POSIX_C_SOURCE	199309L
 #include "sleep.h"