How to add missing / in htaccess?

I know there's some code to automatically add a / to un-closed directories, for example:

This works:

http://www.desktopwallpaper.org/category/Nature/

HTML:

This pulls up a 404 error because missing the last /:

http://www.desktopwallpaper.org/category/Nature

HTML:

Thanks guys!

 

Any help? I guess isn't so complex? I can pay a couple of bucks if interested?

 

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^(.+[^/])$ http://www.yourdomainname.com/$1/ [R,L]

 

Thanks that worked.

 

No problem