diff --git a/polyp/winsock.h b/polyp/winsock.h
index 89ef7ba0b..b1e0f7d44 100644
--- a/polyp/winsock.h
+++ b/polyp/winsock.h
@@ -9,6 +9,7 @@
 #define ECONNABORTED    WSAECONNABORTED
 #define ENETRESET       WSAENETRESET
 #define EINPROGRESS     WSAEINPROGRESS
+#define EAFNOSUPPORT    WSAEAFNOSUPPORT
 #define ETIMEDOUT       WSAETIMEDOUT
 #define ECONNREFUSED    WSAECONNREFUSED
 #define EHOSTUNREACH    WSAEHOSTUNREACH