diff --git a/qutebrowser/keyinput/modeparsers.py b/qutebrowser/keyinput/modeparsers.py
index f56ad6ca2..c6ede2692 100644
--- a/qutebrowser/keyinput/modeparsers.py
+++ b/qutebrowser/keyinput/modeparsers.py
@@ -279,10 +279,11 @@ class MarkKeyParser(keyparser.BaseKeyParser):
 
         return True
 
+    @pyqtSlot(str)
     def on_keyconfig_changed(self, mode):
         """MarkKeyParser has no config section (no bindable keys)."""
         pass
 
     def execute(self, cmdstr, _keytype, count=None):
         """Should never be called on MarkKeyParser."""
-        raise NotImplementedError
+        assert False
diff --git a/qutebrowser/mainwindow/tabbedbrowser.py b/qutebrowser/mainwindow/tabbedbrowser.py
index a95fcd2b4..fb5e86db5 100644
--- a/qutebrowser/mainwindow/tabbedbrowser.py
+++ b/qutebrowser/mainwindow/tabbedbrowser.py
@@ -673,6 +673,7 @@ class TabbedBrowser(tabwidget.TabWidget):
         if key.isupper() and key in self._global_marks:
             point, url = self._global_marks[key]
 
+            @pyqtSlot(bool)
             def callback(ok):
                 if ok:
                     self.cur_load_finished.disconnect(callback)