Compact uses a different part. Interesting note... I tried to order a spurred hammer for my usp .40c from HK. They would sell me the part, but they required my to send in my gun AND they would not return the original bobbed hammer.
So... if you can buy the part from a third party and keep your original, do it. It is not difficult to change the part, but you might want to have a smith do it, and you can change the hammer spring to a Wolff at the same time.
Yo