Jumping is slightly faster than running due to friction

I have a 2D character controller that uses addForce to run and sets a clamp to limit run speed. It all works great on the ground. But - due to friction, my character moves slightly faster on the x axis while airborne. So for example, my x velocity will be 13.8 on land and 14.0 in the air. I need tips on how I can prevent this. I'd like them both to be exactly the same (like in mario, or any other platformer worth its weight in salt).