diff --git a/pykolab/auth/ldap/__init__.py b/pykolab/auth/ldap/__init__.py
--- a/pykolab/auth/ldap/__init__.py
+++ b/pykolab/auth/ldap/__init__.py
@@ -246,6 +246,9 @@
                     level=8
                 )
 
+            # Remove referrals
+            _result_data = [_e for _e in _result_data if _e[0] is not None]
+
             if len(_result_data) == 1:
                 (entry_dn, entry_attrs) = _result_data[0]