diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index 6e7d4f4a33..9790d01809 100644
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -6799,6 +6799,13 @@ addrdataset(dns_db_t *db, dns_dbnode_t *node, dns_dbversion_t *version,
 	INSIST(rbtversion == NULL || rbtversion->rbtdb == rbtdb);
 
 	if (rbtdb->common.methods == &zone_methods) {
+		/*
+		 * SOA records are only allowed at top of zone.
+		 */
+		if (rdataset->type == dns_rdatatype_soa &&
+		    node != rbtdb->origin_node) {
+			return (DNS_R_NOTZONETOP);
+		}
 		RWLOCK(&rbtdb->tree_lock, isc_rwlocktype_read);
 		REQUIRE(((rbtnode->nsec == DNS_RBT_NSEC_NSEC3 &&
 			  (rdataset->type == dns_rdatatype_nsec3 ||