go back one step with folders in php

Hey,

So I have this script where I need to include() a file which is located in a folder previous to the one I'm including from. Now I've tried:

include('./functions.php');

but that didn't work.

This is the structure of my root folder

root

/mufnacka
- lots of files

/cms
- lots of files
- functions.php (file i want to include in...)

/startsida
- admin_start (...this document)



Thanks!