diff --git a/services/univention-s4-connector/modules/univention/s4connector/s4/main.py b/services/univention-s4-connector/modules/univention/s4connector/s4/main.py
index 78710c6fc3..b7a2df3146 100755
--- a/services/univention-s4-connector/modules/univention/s4connector/s4/main.py
+++ b/services/univention-s4-connector/modules/univention/s4connector/s4/main.py
@@ -63,7 +63,11 @@ sys.path = ['/etc/univention/%s/s4/' % CONFIGBASENAME] + sys.path
 
 
 import mapping
-
+try:
+    import localmapping
+    localmapping.adjustmapping(mapping.s4_mapping)
+except ImportError:
+    pass
 
 def bind_stdout():
 	if options.daemonize:
--- /dev/null	2019-04-09 14:30:04.743229977 +0200
+++ /etc/univention/connector/s4/localmapping.py	2019-04-29 17:24:46.422203774 +0200
@@ -0,0 +1,16 @@
+import univention.s4connector
+
+def adjustmapping(s4_mapping):
+    s4_mapping['user'].attributes['uidNumber'] = univention.s4connector.attribute (
+                                                            ucs_attribute='uidNumber',
+                                                            ldap_attribute='uidNumber',
+                                                            con_attribute='uidNumber',
+                                                            single_value=True,
+                                                    )
+
+    s4_mapping['group'].attributes['gidNumber'] = univention.s4connector.attribute (
+                                                            ucs_attribute='gidNumber',
+                                                            ldap_attribute='gidNumber',
+                                                            con_attribute='gidNumber',
+                                                            single_value=True,
+                                                    )