diff --git a/qutebrowser/browser/commands.py b/qutebrowser/browser/commands.py
index 5c97aaf53..a53cfc75e 100644
--- a/qutebrowser/browser/commands.py
+++ b/qutebrowser/browser/commands.py
@@ -1190,11 +1190,11 @@ class CommandDispatcher:
             if config.val.tabs.wrap:
                 new_idx %= self._count()
         else:
-            assert isinstance(index, int)
             # absolute moving
             if count is not None:
                 new_idx = count - 1
             elif index is not None:
+                assert isinstance(index, int)
                 new_idx = index - 1 if index >= 0 else index + self._count()
             else:
                 new_idx = 0