I am trying to find a formula for tying things up. Given an ideal gas like helium or nitrogen gas (diatomic) how can I find its enthalpy simply given internal energy?

I remember it was once taught in thermodynamics class but I cannot find the reference material anymore; I've tried searching on the net too.

I tried tying things up though:

PV = mRT
H = U + PV
H = U + mRT

Is this right? Am I missing anything? is there another more elegant way?