diff --git a/qutebrowser/browser/commands.py b/qutebrowser/browser/commands.py
index 56812f056..faddfcdd5 100644
--- a/qutebrowser/browser/commands.py
+++ b/qutebrowser/browser/commands.py
@@ -86,6 +86,7 @@ class CommandDispatcher:
 
     def _set_current_index(self, idx):
         """Convenience method to set the current widget index."""
+        cmdutils.check_overflow(idx, 'int')
         return self._tabbed_browser.setCurrentIndex(idx)
 
     def _current_index(self):