Platform independent way of referring to root?

I would like to refer to a root folder in my ignore globs in a platform independent way. I assumed that I could use the glob '/exclude/**' but unfortunately, that doesn't work on Windows.

On Windows, I need to use '//?/C:/exclude/**', I would prefer to use '/exclude/**' on both Windows and Linux.

What is odd is that include globs starting with '/' to refer to the root work fine on Windows, it only doesn't work for ignore globs.

Are there any GlobOptions I'm overlooking that will allow '/exclude/**' to work on Windows?