Bucks Fizz – Making Your Mind Up Lyrics. It's true that grammarians normally support @SovereignSun's position on this matter, but in practice, native speakers often ignore this principle in colloquial speech. If you check out I have made up* my mind* in Google Books you'll find the "incorrect" version I have made* my mind up* only occurs half as often, but that preference is reversed if we consider the more informal versions with *I've* instead of *I have*. So approximately, both versions are "fine".
– FumbleFingersSep 08 '17 at 16:06