diff --git a/services/univention-s4-connector/modules/univention/s4connector/__init__.py b/services/univention-s4-connector/modules/univention/s4connector/__init__.py
index 91a2346011..b6e5891bca 100644
--- a/services/univention-s4-connector/modules/univention/s4connector/__init__.py
+++ b/services/univention-s4-connector/modules/univention/s4connector/__init__.py
@@ -1534,7 +1534,8 @@ class ucs:
 			result = False
 			if object['modtype'] == 'add':
 				ud.debug(ud.LDAP, ud.INFO, "sync_to_ucs: lock S4 guid: %s" % guid)
-				self.lockingdb.lock_s4(guid)
+				if not self.lockingdb.is_s4_locked(guid):
+					self.lockingdb.lock_s4(guid)
 
 			if hasattr(self.property[property_type], "ucs_sync_function"):
 				result = self.property[property_type].ucs_sync_function(self, property_type, object)
diff --git a/services/univention-s4-connector/modules/univention/s4connector/s4/__init__.py b/services/univention-s4-connector/modules/univention/s4connector/s4/__init__.py
index b93b07f723..6b0f08fb63 100644
--- a/services/univention-s4-connector/modules/univention/s4connector/s4/__init__.py
+++ b/services/univention-s4-connector/modules/univention/s4connector/s4/__init__.py
@@ -2512,7 +2512,8 @@ class s4(univention.s4connector.ucs):
 			ud.debug(ud.LDAP, ud.INFO, "sync_from_ucs: add object: %s" % object['dn'])
 
 			ud.debug(ud.LDAP, ud.INFO, "sync_from_ucs: lock UCS entryUUID: %s" % entryUUID)
-			self.lockingdb.lock_ucs(entryUUID)
+			if not self.lockingdb.is_ucs_locked(entryUUID):
+				self.lockingdb.lock_ucs(entryUUID)
 
 			self.addToCreationList(object['dn'])