diff --git a/lib/ldap/group.rb b/lib/ldap/group.rb
index a1c5419f4c4b..e92aa58ad507 100644
--- a/lib/ldap/group.rb
+++ b/lib/ldap/group.rb
@@ -112,7 +112,7 @@ def user_roles(mapping, filter: nil)
     #
     # @return [String, nil] The active or found filter or nil if none could be found.
     def filter
-      @filter ||= lookup_filter(['(objectClass=group)', '(objectClass=posixgroup)', '(objectClass=organization)'])
+      @filter ||= lookup_filter(['(objectClass=groupOfUniqueNames)', '(objectClass=group)', '(objectClass=posixgroup)', '(objectClass=organization)'])
     end
 
     # The active uid attribute of the instance. If none give on initialization an automatic lookup is performed.