Repairing an interior wooden window sill

We have a window sill that is in need of repair. Water seeped down through the window and eventually damaged an area of the window sill, not that bad but it is a little rippled. We have since had an overhang built over the window. That is not the problem..can I just sand the damage to the sill and fill it in with wood filler and then sand, prime and paint? We are in the process of selling our home so I would like to fix this before we get any people looking at it...thank you