diff --git a/runtime/ftplugin/aap.vim b/runtime/ftplugin/aap.vim
index 9b20ec4..b5065e5 100644
--- a/runtime/ftplugin/aap.vim
+++ b/runtime/ftplugin/aap.vim
@@ -1,7 +1,7 @@
 " Vim filetype plugin file
 " Language:	Aap recipe
 " Maintainer:	Bram Moolenaar <Bram@vim.org>
-" Last Change:	2013 Apr 05
+" Last Change:	2021 Nov 14
 
 " Only do this when not done yet for this buffer
 if exists("b:did_ftplugin")
@@ -11,8 +11,9 @@
 " Don't load another plugin for this buffer
 let b:did_ftplugin = 1
 
-" Reset 'formatoptions', 'comments' and 'expandtab' to undo this plugin.
-let b:undo_ftplugin = "setl fo< com< et<"
+" Reset 'formatoptions', 'comments', 'commentstring' and 'expandtab' to undo
+" this plugin.
+let b:undo_ftplugin = "setl fo< com< cms< et<"
 
 " Set 'formatoptions' to break comment lines but not other lines,
 " and insert the comment leader when hitting <CR> or using "o".
@@ -20,6 +21,12 @@
 
 " Set 'comments' to format dashed lists in comments.
 setlocal comments=s:#\ -,m:#\ \ ,e:#,n:#,fb:-
+setlocal commentstring=#\ %s
 
 " Expand tabs to spaces to avoid trouble.
 setlocal expandtab
+
+if (has("gui_win32") || has("gui_gtk")) && !exists("b:browsefilter")
+  let b:browsefilter = "Aap Recipe Files (*.aap)\t*.aap\nAll Files (*.*)\t*.*\n"
+  let b:undo_ftplugin ..= " | unlet! b:browsefilter"
+endif