diff --git a/kitty/layout/splits.py b/kitty/layout/splits.py
index 0aad98603..03dd0bf88 100644
--- a/kitty/layout/splits.py
+++ b/kitty/layout/splits.py
@@ -639,6 +639,7 @@ def layout_action(self, action_name: str, args: Sequence[str], all_windows: Wind
                     if count == 2:  # special case, a single split
                         pair = self.pairs_root.pair_for_window(wg.id)
                         if pair is not None:
+                            pair.horizontal = horizontal
                             if which in ('left', 'top'):
                                 if pair.one != wg.id:
                                     pair.one, pair.two = pair.two, pair.one