diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 45a115ec566..03fa622031a 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2011-11-18  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* files-x.el (modify-file-local-variable): Obey commenting conventions.
+
 2011-11-17  Glenn Morris  <rgm@gnu.org>
 
 	* emacs-lisp/autoload.el (autoload-generate-file-autoloads):
diff --git a/lisp/files-x.el b/lisp/files-x.el
index a6320b32e50..ca847097184 100644
--- a/lisp/files-x.el
+++ b/lisp/files-x.el
@@ -149,7 +149,7 @@ from the Local Variables list ignoring the input argument VALUE."
 
 	(goto-char (point-max))
 	(let ((comment-style 'plain)
-	      (comment-start (or comment-start ";;; ")))
+	      (comment-start (or comment-start ";; ")))
 	  (comment-region
 	   (prog1 (setq beg (point))
 	     (insert "\nLocal Variables:\nEnd:\n"))