diff --git a/src/OpenThreads/win32/Win32ConditionPrivateData.h b/src/OpenThreads/win32/Win32ConditionPrivateData.h
index 0c2ec6bf0..5a14b74e0 100644
--- a/src/OpenThreads/win32/Win32ConditionPrivateData.h
+++ b/src/OpenThreads/win32/Win32ConditionPrivateData.h
@@ -21,6 +21,7 @@
 
 #ifndef _WINDOWS_
 #define WIN32_LEAN_AND_MEAN
+#define _WIN32_WINNT 0x0400
 #include <windows.h>
 #endif