diff --git a/src/window.c b/src/window.c
index d776cd7119e..1d9104cc779 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5161,7 +5161,7 @@ window_set_parent_and_normal_sizes (Lisp_Object parent)
   /* Normal size left for yet unprocessed windows.  */
   double remainder = 1.0;
 
-  if (w->horizontal)
+  if (p->horizontal)
     {
       while (true)
 	{