# Isobaric-isothermal ensemble with degeneracy

I've been studying statistical mechanics for a while, the topic is very far from what I've learned till now so my questions may be superficial. When trying to see what my entropy is in an isobaric-isothermal ensemble, which turns out to be applicable in reactive systems, if I write my partition function $$\Delta$$ without the degeneracy factor $$\Omega$$, the answer I get from

$$S = \sum p_i\ln p_i$$

is

$$G = -T\ln\Delta$$

(with $$T$$ in energy units, $$k_\mathrm{B} = 1$$). However, if I take my systems to be in favor of a state or degenerate, I get

$$G + T\ln\Omega = -T\ln\Delta$$

Anywhere I read about this ensemble, the relationship for $$G$$ is in the first form and not the second, can someone give hints to some reading for what I'm missing here?