diff --git a/lib/isc/include/isc/socket.h b/lib/isc/include/isc/socket.h
index b0392f3dcb..dd7ed1ce58 100644
--- a/lib/isc/include/isc/socket.h
+++ b/lib/isc/include/isc/socket.h
@@ -102,6 +102,10 @@ struct isc_socket_connev {
 	isc_result_t		result;		/* OK, EOF, whatever else */
 };
 
+#define ISC_SOCKEVENTATTR_TRUNC			0x8000000U
+#define ISC_SOCKEVENTATTR_CTRUNC		0x4000000U
+#define ISC_SOCKEVENTATTR_TIMESTAMP		0x2000000U
+
 #define ISC_SOCKEVENT_ANYEVENT  (0)
 #define ISC_SOCKEVENT_RECVDONE	(ISC_EVENTCLASS_SOCKET + 1)
 #define ISC_SOCKEVENT_SENDDONE	(ISC_EVENTCLASS_SOCKET + 2)