diff --git a/gtk/gtkbox.c b/gtk/gtkbox.c
index f4e88eb..ef939fe 100644
--- a/gtk/gtkbox.c
+++ b/gtk/gtkbox.c
@@ -1123,6 +1123,8 @@ gtk_box_pack (GtkBox      *box,
   gtk_widget_child_notify (child, "pack-type");
   gtk_widget_child_notify (child, "position");
   gtk_widget_thaw_child_notify (child);
+
+  gtk_widget_queue_compute_expand (GTK_WIDGET (box));
 }
 
 static void
