diff --git a/src/knot/updates/ddns.c b/src/knot/updates/ddns.c
index a55faa545d455829c4761767cd8535c1cd5fd5b8..e16efcbce2120f8f3964ce1979b442d5693ac982 100644
--- a/src/knot/updates/ddns.c
+++ b/src/knot/updates/ddns.c
@@ -895,7 +895,7 @@ static int knot_ddns_add_rr_merge_normal(knot_rrset_t *node_rrset_copy,
 	/* First check if the TTL of the new RR is equal to that of the first
 	 * RR in the node's RRSet. If not, refuse the UPDATE.
 	 */
-	if (knot_rrset_rr_ttl(*rr_copy, 1)
+	if (knot_rrset_rr_ttl(*rr_copy, 0)
 	    != knot_rrset_rr_ttl(node_rrset_copy, 0)) {
 		char type_str[16] = { '\0' };
 		knot_rrtype_to_string(knot_rrset_type(*rr_copy), type_str,