diff --git a/src/calibre/gui2/library/delegates.py b/src/calibre/gui2/library/delegates.py
index 91d774b04b..430793aab7 100644
--- a/src/calibre/gui2/library/delegates.py
+++ b/src/calibre/gui2/library/delegates.py
@@ -438,7 +438,7 @@ class CcDateDelegate(QStyledItemDelegate, UpdateEditorGeometry):  # {{{
         elif _format == 'iso':
             self.format = internal_iso_format_string()
         else:
-            self.format = format
+            self.format = _format
 
     def displayText(self, val, locale):
         d = qt_to_dt(val)