Add closet to increase value?

[Joe Edwards-Hoff]

I'm trying to help out a friend. He has a 500sqft home with two bedrooms, but one technically isn't due to it not having a closet. The typical house size in his area is about 2.5 bed and 1.25 bath averaged out.

If he plans on selling the house in the future, is it worth adding a closet so that his house would technically be a 2 bed vs a 1. A final factor is that his house is so small, adding a closet internally will reduce floor space.