How to approach compensation difference?

Hello all. Looking for some advice on how to approach this topic of compensation difference. I definitively found out that another junior who just joined is making 25% more comp than me. He has less skills, knowledge, is 2 years less experienced than me, and is a rank below me.

All of my reviews have been excellent and was told that I am a top bucket contributor. I knew this was true prior to the new junior joining. How should I go about addressing this difference?

I am not sure if adjustments have been made in 2018 since that won't be known till march, but if there are no adjustments, what should I say?

My team (including my direct manager) are all very close personally. We hang out on the weekends, haven't had any professional problems and have all been working together well for 5 years.