diff --git a/src/apprt/gtk/Window.zig b/src/apprt/gtk/Window.zig
index 129c149e7..1300aed57 100644
--- a/src/apprt/gtk/Window.zig
+++ b/src/apprt/gtk/Window.zig
@@ -1058,7 +1058,7 @@ fn gtkActionSplitUp(
     _: ?*glib.Variant,
     self: *Window,
 ) callconv(.C) void {
-    self.performBindingAction(.{ .new_split = .right });
+    self.performBindingAction(.{ .new_split = .up });
 }
 
 fn gtkActionToggleInspector(