diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 017a63e..eac5b4e 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -475,6 +475,9 @@
 }
 
 #ifdef MS_WINDOWS
+#ifndef WSAEAGAIN
+#define WSAEAGAIN WSAEWOULDBLOCK
+#endif
 #define CHECK_ERRNO(expected) \
     (WSAGetLastError() == WSA ## expected)
 #else