diff --git a/lib/ns/client.c b/lib/ns/client.c
index 8680cd6c47..88327fbc7b 100644
--- a/lib/ns/client.c
+++ b/lib/ns/client.c
@@ -2139,7 +2139,7 @@ ns__client_request(isc_nmhandle_t *handle, isc_result_t eresult,
 	default:
 		dns_rdataclass_format(client->message->rdclass, classbuf,
 				      sizeof(classbuf));
-		ns_client_dumpmessage(client, NULL);
+		ns_client_dumpmessage(client, "");
 		ns_client_log(client, NS_LOGCATEGORY_CLIENT,
 			      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(1),
 			      "invalid message class: %s", classbuf);
@@ -2177,7 +2177,7 @@ ns__client_request(isc_nmhandle_t *handle, isc_result_t eresult,
 		ns_client_log(client, NS_LOGCATEGORY_CLIENT,
 			      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(1),
 			      "no matching view in class '%s'", classname);
-		ns_client_dumpmessage(client, NULL);
+		ns_client_dumpmessage(client, "");
 		ns_client_extendederror(client, DNS_EDE_PROHIBITED, NULL);
 		ns_client_error(client, notimp ? DNS_R_NOTIMP : DNS_R_REFUSED);
 		return;