How easiest to make wall behind removed oil tank look less horrible (storage room)

[buffi]

We have removed an oil tank in the basement, and behind the tank it's unplastered, which looks pretty rough:
http://i.imgur.com/8hL9zYs.jpg

We plan to use this area for storage for now, but it would be nice to do something simple to make it look a bit better. I'd rather not replaster the entire wall, but can we cheat a little and throw some plaster on the unplastered area and then repaint the walls, or will it look terrible?

 

[Oldboy]

What kind of wall is underneath? I think it looks plastered, but not painted? It was possibly only at the very bottom against the floor that it looked a bit strange (unplastered?)...

 

[Sam_u_El]

I agree with Oldboy; I also think it looks polished. Paint the entire surface with the right* paint and it should be fine.

*paint that allows moisture to pass through.