diff --git a/lib/ns/query.c b/lib/ns/query.c
index 3af20bc4c9..c056a59e6f 100644
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -7808,10 +7808,17 @@ query_respond(query_ctx_t *qctx) {
 	query_addnoqnameproof(qctx);
 
 	/*
-	 * We shouldn't ever fail to add 'rdataset'
-	 * because it's already in the answer.
-	 */
-	INSIST(qctx->rdataset == NULL || QUERY_ANSWERED(&qctx->client->query));
+	 * 'qctx->rdataset' will only be non-NULL here if the ANSWER section of
+	 * the message to be sent to the client already contains an RRset with
+	 * the same owner name and the same type as 'qctx->rdataset'.  This
+	 * should never happen, with one exception: when chasing DNAME records,
+	 * one of the DNAME records placed in the ANSWER section may turn out
+	 * to be the final answer to the client's query, but we have no way of
+	 * knowing that until now.  In such a case, 'qctx->rdataset' will be
+	 * freed later, so we do not need to free it here.
+	 */
+	INSIST(qctx->rdataset == NULL || qctx->qtype == dns_rdatatype_dname ||
+	       QUERY_ANSWERED(&qctx->client->query));
 
 	query_addauth(qctx);