diff --git a/src/calibre/gui2/tag_browser/view.py b/src/calibre/gui2/tag_browser/view.py
index 865524f1eb..d691cbcd70 100644
--- a/src/calibre/gui2/tag_browser/view.py
+++ b/src/calibre/gui2/tag_browser/view.py
@@ -704,7 +704,7 @@ class TagsView(QTreeView):  # {{{
                         self._model.set_value_icon(key, TEMPLATE_ICON_INDICATOR, d.rule[2], False)
                         self.recount()
                     return
-                (icon_file_name, for_children) = extra
+                (icon_file_name, for_children) = extra if extra is not None else (None, None)
                 item_val, desired_file_name = make_icon_name(key, index)
                 if icon_file_name is None:
                     # User wants to specify a specific icon