Is the name Mackenzie too "girlish" for a boy?

I have a guy friend named Mackenzie, he goes by Mack. Today it's known as a girl name, the average person doesn't even know names like Mackenzie, Ashley, Shelby, etc are boys names at all and would think it's an absurd name for anything but a girl (or at least in America). I wouldn't use an original boy name on a girl, even if it was now considered a girl name, but I also wouldn't use a now considered girl name on a boy, even it it was originally a boy name.