Hi. You will get a flat or g sharp depending on what key you are using. You generally don't mix sharps and flats in a key. For example - E major has a G# but Eb major has an Ab. Enharmonically they are the same, but they are not the same note. It's one of those dubious music theory things, I am afraid. But essentially you can blame 17th century theorists for the issue . It was about that time that our modern music harmony theory was created.