I have a degree but it isn't actually what it looks like it is. How do I list it on my CV? Due to various department sortings and organizations, I have a degree that is, functionally, a computer science degree but because it belonged to the College of Mathematics, the degree is formally "Mathematics".

Unfortunately this leads to many employers thinking that I have a mathematics background when the reality is far from this: I don't think like a mathematician or particularly enjoy its work.

Is there something I can do with my CV to reduce this bias? Is it as simple as changing "Mathematics" to "Computer science" even if it isn't the official title of the degree? Are there other options?
I would list it directly with the degree. I have a similar issue in that my degree is Geodetic Science, but my focus was in (at the time) computer-assisted mapping, now known as GIS. People try to call me a geodesist, but I'm not really. I would use something like:

M.S. Mathematics (specialty: Computer Science)

Edit: I finally remembered what the various tracks were called in our department--a concentration, not a specialty. Other synonyms include focus, even research or research topic.