diff --git a/qutebrowser/utils/objreg.py b/qutebrowser/utils/objreg.py
index 7c561b139..98cbe9cb2 100644
--- a/qutebrowser/utils/objreg.py
+++ b/qutebrowser/utils/objreg.py
@@ -63,7 +63,7 @@ class WindowAccessHistory():
         except ValueError:
             pass
 
-    def last(self) -> 'mainwindow.MainWindow':
+    def last(self) -> Optional['mainwindow.MainWindow']:
         """Return the last window from the access history.
 
         Prune any None values and windows that are shutting down and