diff --git a/window.c b/window.c
index 1d9e84f9..7fc438ea 100644
--- a/window.c
+++ b/window.c
@@ -2091,7 +2091,7 @@ window_pane_tiled_geometry(struct window *w, struct window_pane *wp,
 	} else if (args_has(args, 'p')) {
 		size = args_strtonum_and_expand(args, 'p', 0, 100, item,
 		    cause);
-		if (cause == NULL)
+		if (*cause == NULL)
 			size = curval * size / 100;
 	}
 	if (*cause != NULL)