If g is a PRG and f is a OWF, is G'(x) = f(g(x)) a PRG?

Just like the title states.

If I have a pseudo-random generator $ g: \sum^n \rightarrow \sum^{2n}$ and a one-way function $ f$ , is $ g'(x)=f(g(x))$ a pseudo-random generator? And why?

My instinct tells me it is, but I can’t really explain why.