Page Referer question

Hello all. I am looking to create script will detect the page from which the user just came so that after they do something on the current page (login) it will send them back to the page they wanted. I was thinking about $_SERVER['HTTP_REFERER'], but php.net says: 'HTTP_REFERER' The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted. Is this a big problem? Is there another technique I could use? Thank you all!