diff --git a/include/winsock.h b/include/winsock.h
index d5c1e0baa48..21e984c3ce9 100644
--- a/include/winsock.h
+++ b/include/winsock.h
@@ -662,6 +662,7 @@ typedef struct WS(WSAData)
 #define SO_RCVTIMEO                0x1006
 #define SO_ERROR                   0x1007
 #define SO_TYPE                    0x1008
+#define SO_BSP_STATE               0x1009
 
 
 #define IOCPARM_MASK               0x7f