diff --git a/lisp/net/dictionary-connection.el b/lisp/net/dictionary-connection.el
index f1d11bf3c57..d433fb3fec8 100644
--- a/lisp/net/dictionary-connection.el
+++ b/lisp/net/dictionary-connection.el
@@ -1,4 +1,4 @@
-;;; dictionary-connection.el --- TCP-based client connection for dictionary
+;;; dictionary-connection.el --- TCP-based client connection for dictionary  -*- lexical-binding:t -*-
 
 ;; Author: Torsten Hilbrich <torsten.hilbrich@gmx.net>
 ;; Keywords: network