diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index df1c9f9..d741d2c 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -390,6 +390,7 @@
 #endif
 
 #ifdef MS_WIN32
+#undef EAFNOSUPPORT
 #define EAFNOSUPPORT WSAEAFNOSUPPORT
 #define snprintf _snprintf
 #endif