diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index cab398e9fa..0b5e0eda77 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -2651,7 +2651,7 @@ class Cache:
             fmts = field.table.book_col_map.get(book_id, ())
             if not fmts:
                 continue
-            mi = self.get_metadata(book_id, get_cover=True, cover_as_data=True)
+            mi = self._get_metadata(book_id, get_cover=True, cover_as_data=True)
             try:
                 path = self._field_for('path', book_id).replace('/', os.sep)
             except: