diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index f99a04adce..36f3df81c4 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -400,6 +400,7 @@ class DB(object):
         defs['gui_restriction'] = defs['cs_restriction'] = ''
         defs['categories_using_hierarchy'] = []
         defs['column_color_rules'] = []
+        defs['column_icon_rules'] = []
         defs['grouped_search_make_user_categories'] = []
         defs['similar_authors_search_key'] = 'authors'
         defs['similar_authors_match_kind'] = 'match_any'