Case insensitive ksort

I looked in the docs but didn't see anything regarding case insensitivity and I fear the functionality doesn't exist. I'm just hoping I'm looking in the wrong place. Is there a way to get ksort to work without regard to case? When I sort an array using ksort, all the upper case keys end up at the top (sorted) and all the lower case keys end up at the bottom (sorted). Ideally, I'd like to see all the keys sorted (and intermixed) regardless of case. Am I going to have to do this manually? Or is there an internal php command that will do it for me? thnx, Christoph