diff --git a/command-log-mode.el b/command-log-mode.el
index 34ec546..50a7bce 100644
--- a/command-log-mode.el
+++ b/command-log-mode.el
@@ -1,4 +1,4 @@
-;;; command-log-mode.el --- log keyboard commands to buffer
+;;; command-log-mode.el --- log keyboard commands to buffer  -*- lexical-binding: t; -*-
 
 ;; homepage: https://github.com/lewang/command-log-mode