diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 9545560bfa..b09813d444 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -8178,6 +8178,7 @@ rctx_dispfail(respctx_t *rctx) {
 	case ISC_R_NETUNREACH:
 	case ISC_R_CONNREFUSED:
 	case ISC_R_CONNECTIONRESET:
+	case ISC_R_INVALIDPROTO:
 	case ISC_R_CANCELED:
 	case ISC_R_SHUTTINGDOWN:
 		rctx->broken_server = rctx->result;