Upgrading from Font Awesome 4.1 to 4.2 - icons appear as boxes

I'm running a simple website that uses Font Awesome icons under 4.1

I'm keen to upgrade to 4.2 ad thought it was just a matter of copying the contents of the 4.2 min.css file into the existing 4.1 min.css file on my server but this has resulted in all the icons appearing as empty boxes.

What could I be doing wrong please?

Solution

Thanks to user Lyrical! Similar set up to you but having checked the location of the font files I found them in a different location. Quick shuffle of files later and everything is fine!