How to increase brightness on Dell Latitude D620 without arrow key?

My Up arrow key doesn't seem to work at all, so I can't use it to increase the brightness with Fn. My down arrow key works just fine though. Is there any alternative to increase the brightness in this situation? I was thinking I could switch the functions of the up and down arrow keys, making the down arrow key (the working one) go up instead of down and thus increasing the brightness. I don't know how to do this, however.