diff --git a/trytond/model/modelsql.py b/trytond/model/modelsql.py
index ab65a0565d..df354e3129 100644
--- a/trytond/model/modelsql.py
+++ b/trytond/model/modelsql.py
@@ -1981,14 +1981,10 @@ class ModelSQL(ModelStorage):
                 'WHERE id IN (' + ','.join(['%s' for x in child_ids]) + ')',
                 child_ids)
 
-        if parent_id is False:
-            cursor.execute('SELECT id FROM "' + self._table + '" WHERE "' +\
-                               field_name + '" IS NULL')
-        else:
-            cursor.execute('SELECT id FROM "' + self._table + '" WHERE "' +\
-                               field_name + '" = %s', (parent_id,))
-        brother_ids = [x[0] for x in cursor.fetchall()]
-
+        # Use root user to by-pass rules
+        brother_ids = self.search(cursor, 0, [
+            (field_name, '=', parent_id),
+            ])
         if brother_ids[-1] != object_id:
             next_id = brother_ids[brother_ids.index(object_id) + 1]
             cursor.execute('SELECT "' + left + '",  "' + right + '" ' \