PHP: How to set current working directory to be same as directory executing the script

I'm in the process of transferring my website from one server to another. I have some php scripts that use the is_readable function which uses the current working directory.

On the old server, when I call getcwd(), it outputs the folder in which the script is being executed. On the new server it outputs the root directory '/'.

I would like to know how I can configure PHP to use the current folder instead of '/'. I don't want to have to change any PHP code that already works on the old server. I can configure the new server, but don't know what settings to change. I'm using apache2, if that helps.

EDIT: It seems as though my working directory is not root like I thought. When I create a testFile.php and echo getcwd() it shows the directory the php file is in. But in my problem file, in the same directory, getcwd() shows up as '/'