diff --git a/ixwebsocket/IXNetSystem.h b/ixwebsocket/IXNetSystem.h
index 203a4e45..f1361d10 100644
--- a/ixwebsocket/IXNetSystem.h
+++ b/ixwebsocket/IXNetSystem.h
@@ -7,6 +7,11 @@
 #pragma once
 
 #ifdef _WIN32
+
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+
 #include <WS2tcpip.h>
 #include <WinSock2.h>
 #include <basetsd.h>