diff --git a/misc/ninja-mode.el b/misc/ninja-mode.el
index ac5318d..71825d5 100644
--- a/misc/ninja-mode.el
+++ b/misc/ninja-mode.el
@@ -1,4 +1,4 @@
-;;; ninja-mode.el --- Major mode for editing .ninja files
+;;; ninja-mode.el --- Major mode for editing .ninja files -*- lexical-binding: t -*-
 
 ;; Package-Requires: ((emacs "24"))