diff --git a/cfg/windows.cfg b/cfg/windows.cfg
index 41bf2a0f1..2159a046e 100644
--- a/cfg/windows.cfg
+++ b/cfg/windows.cfg
@@ -3568,5 +3568,6 @@ HFONT CreateFont(
   <define name="DECLARE_DYNAMIC_CLASS(x)" value=""/>
   <define name="DECLARE_DYNCREATE(x)" value=""/>
   <define name="INVALID_HANDLE_VALUE" value="0"/>
+  <define name="INVALID_SOCKET" value="0"/>
   <define name="WINAPI" value=""/>
 </def>