diff --git a/services/univention-s4-connector/modules/univention/s4connector/s4/dns.py b/services/univention-s4-connector/modules/univention/s4connector/s4/dns.py
index c44dbbbd5d..8394598478 100644
--- a/services/univention-s4-connector/modules/univention/s4connector/s4/dns.py
+++ b/services/univention-s4-connector/modules/univention/s4connector/s4/dns.py
@@ -546,7 +546,7 @@ def __pack_soaRecord(object, dnsRecords):
 		soa = soaRecord.split(' ')
 		mname = soa[0]
 		rname = soa[1]
-		serial = int(soa[2])
+		serial = int(soa[2]) -1 if int(soa[2]) > 0 else 0
 		refresh = int(soa[3])
 		retry = int(soa[4])
 		expire = int(soa[5])
@@ -798,7 +798,7 @@ def s4_zone_create(s4connector, object):
 
 	__pack_txtRecord(object, dnsRecords)
 
-	s4connector.lo_s4.modify(soa_dn, [('dnsRecord', old_dnsRecords, dnsRecords)])
+	s4connector.lo_s4.modify(soa_dn, [('dnsRecord', old_dnsRecords, list(set(dnsRecords)))])
 
 	return True