How do I deal with a messy coworker?

I'm always cleaning up after him and I've asked him numerous times to clean up his messes with no success. But I'm not his mother and shouldn't have to clean up after him. Do I take it to the boss? Because if the boss says something to him he'll know that I said something. It's not only the mess that's bothering me but I don't know if the boss thinks if it's me too that's making the messes. How do I resolve this amicably? I still need to work with him.