diff --git a/runtime/ftplugin/hgcommit.vim b/runtime/ftplugin/hgcommit.vim
index d5a6c0a383..1bbb6faaae 100644
--- a/runtime/ftplugin/hgcommit.vim
+++ b/runtime/ftplugin/hgcommit.vim
@@ -1,10 +1,11 @@
 " Vim filetype plugin file
 " Language:	hg (Mercurial) commit file
 " Maintainer:	Ken Takata <kentkt at csc dot jp>
-" Last Change:	2016 Jan 6
+" Last Change:	2025 Jun 8
 " Filenames:	hg-editor-*.txt
 " License:	VIM License
 " URL:		https://github.com/k-takata/hg-vim
+" 2025 Jun 18 by Vim Project: update commentstring option (#17480)
 
 if exists("b:did_ftplugin")
   finish
@@ -13,4 +14,7 @@ let b:did_ftplugin = 1
 
 setlocal nomodeline
 
-let b:undo_ftplugin = 'setl modeline<'
+setlocal comments=:HG\:
+setlocal commentstring=HG:\ %s
+
+let b:undo_ftplugin = 'setl modeline< com< cms<'