diff --git a/services/univention-s4-connector/conffiles/etc/univention/s4connector/s4/mapping.py b/services/univention-s4-connector/conffiles/etc/univention/s4connector/s4/mapping.py
index ff74ffd..2aa8f5f 100644
--- a/services/univention-s4-connector/conffiles/etc/univention/s4connector/s4/mapping.py
+++ b/services/univention-s4-connector/conffiles/etc/univention/s4connector/s4/mapping.py
@@ -1103,7 +1103,7 @@
 ignore_filter = ''
 for dns in configRegistry.get('connector/s4/mapping/dc/ignorelist', '').split(','):
 	if dns:
-		ignore_filter += '(%s)' % (dns)
+		ignore_filter += '(cn=%s)' % (dns)
 if ignore_filter:
 	print "			ignore_filter='(|%s)'," % ignore_filter
 @!@