diff --git a/tailbone/views/batch.py b/tailbone/views/batch.py
index 127e66dd..543d118e 100644
--- a/tailbone/views/batch.py
+++ b/tailbone/views/batch.py
@@ -354,7 +354,7 @@ class BatchMasterView(MasterView):
             return HTML.tag('p', c=tags.link_to("Delete all rows matching current search", url))
 
     def make_row_grid_tools(self, batch):
-        return self.make_default_row_grid_tools(obj) + self.make_batch_row_grid_tools(batch)
+        return (self.make_default_row_grid_tools(batch) or '') + (self.make_batch_row_grid_tools(batch) or '')
 
     def redirect_after_edit(self, batch):
         """