diff --git a/src/include/lwip/sockets.h b/src/include/lwip/sockets.h
index da053b57..5db92cca 100644
--- a/src/include/lwip/sockets.h
+++ b/src/include/lwip/sockets.h
@@ -209,6 +209,7 @@ struct linger {
 #define MSG_OOB        0x04    /* Unimplemented: Requests out-of-band data. The significance and semantics of out-of-band data are protocol-specific */
 #define MSG_DONTWAIT   0x08    /* Nonblocking i/o for this operation only */
 #define MSG_MORE       0x10    /* Sender will send more */
+#define MSG_NOSIGNAL   0x20    /* Uninmplemented: Requests not to send the SIGPIPE signal if an attempt to send is made on a stream-oriented socket that is no longer connected. */
 
 
 /*