diff --git a/runtime/ftplugin/nginx.vim b/runtime/ftplugin/nginx.vim
index e808db1..525d0fd 100644
--- a/runtime/ftplugin/nginx.vim
+++ b/runtime/ftplugin/nginx.vim
@@ -2,5 +2,8 @@
 " Language: nginx.conf
 " Maintainer: Chris Aumann <me@chr4.org>
 " Last Change: Apr 15, 2017
+"              2023 Aug 28 by Vim Project (undo_ftplugin)
 
 setlocal commentstring=#\ %s
+
+let b:undo_ftplugin = "setlocal commentstring<"