Is it possible to make Arduino use the same com port all the time

Sometimes when I'm programing the controller it reuses the same port and other times the port changes, it's kind of a pain. I'm wondering if there is away to tell the OS that when it sees Arduino to always assign to comport 3 or something like that?

The only times I have had that happen is when I plug the Aruino into a different USB port. Is this what you are doing?