diff --git a/src/calibre/gui2/tag_mapper.py b/src/calibre/gui2/tag_mapper.py
index bece16b9e2..6de73f1fd9 100644
--- a/src/calibre/gui2/tag_mapper.py
+++ b/src/calibre/gui2/tag_mapper.py
@@ -389,4 +389,6 @@ if __name__ == '__main__':
         {'action':'replace', 'query':'moose', 'match_type':'one_of', 'replace':'xxxx'},
     ]
     d.exec_()
+    from pprint import pprint
+    pprint(d.rules)
     del d, app