diff --git a/header.lisp b/header.lisp
index 9a396c3621fbda322cf837c9ac798964af4ac5a6..2e1c8ed4fe297b6f02bb72b05201c16208eaafbe 100644
--- a/header.lisp
+++ b/header.lisp
@@ -1,4 +1,4 @@
-;;; -*- mode: Common-Lisp; Base: 10 ; Syntax: ANSI-Common-Lisp -*-
+;;; -*- mode: Common-Lisp; Base: 10 ; Syntax: ANSI-Common-Lisp ; buffer-read-only: t; -*-
 ;;; This is ASDF 3.1.0.63: Another System Definition Facility.
 ;;;
 ;;; Feedback, bug reports, and patches are all welcome: