diff --git a/lib/dns/include/dns/events.h b/lib/dns/include/dns/events.h
index 016e026b64..c32e0d1491 100644
--- a/lib/dns/include/dns/events.h
+++ b/lib/dns/include/dns/events.h
@@ -34,6 +34,7 @@ ISC_LANG_BEGINDECLS
 #define DNS_EVENT_QUERY				(ISC_EVENTCLASS_DNS + 4)
 #define DNS_EVENT_QUERYDONE			(ISC_EVENTCLASS_DNS + 5)
 #define DNS_EVENT_DISPATCH			(ISC_EVENTCLASS_DNS + 6)
+#define DNS_EVENT_TCPMSG			(ISC_EVENTCLASS_DNS + 7)
 
 #define DNS_EVENT_FIRSTEVENT			(ISC_EVENTCLASS_DNS + 0)
 #define DNS_EVENT_LASTEVENT			(ISC_EVENTCLASS_DNS + 65535)