diff --git a/include/types/connection.h b/include/types/connection.h
index 13cbf73..624e01e 100644
--- a/include/types/connection.h
+++ b/include/types/connection.h
@@ -243,7 +243,12 @@
 	CO_SRC_BIND        = 0x0008,    /* bind to a specific source address when connecting */
 };
 
-/* flags that can be passed to xprt->snd_buf() */
+/* flags that can be passed to xprt->rcv_buf() and mux->rcv_buf() */
+enum {
+	CO_RFL_BUF_WET     = 0x0001,    /* Buffer still has some output data present */
+};
+
+/* flags that can be passed to xprt->snd_buf() and mux->snd_buf() */
 enum {
 	CO_SFL_MSG_MORE    = 0x0001,    /* More data to come afterwards */
 	CO_SFL_STREAMER    = 0x0002,    /* Producer is continuously streaming data */