diff --git a/src/calibre/library/caches.py b/src/calibre/library/caches.py
index 1e3b37c89b..4f0cc82fa9 100644
--- a/src/calibre/library/caches.py
+++ b/src/calibre/library/caches.py
@@ -913,8 +913,9 @@ class ResultCache(SearchQueryParser): # {{{
 
     def set(self, row, col, val, row_is_id=False):
         id = row if row_is_id else self._map_filtered[row]
-        self._data[id][col] = val
-        self._data[id].refresh_composites()
+        d = self._data[id]
+        d[col] = val
+        d.refresh_composites()
 
     def get(self, row, col, row_is_id=False):
         id = row if row_is_id else self._map_filtered[row]