How to stop appending numbers to filenames

At some point in time, Photoshop began appending sequential numbers (-1, -2, -3, etc) to filenames when a file is opened multiple times during the same session. It didn't do this before. It seems to assume I want to create a new version of the file when I Save As. I don't. I want to overwrite the old version. I have to edit the filename before saving, and if I'm not paying attention, I end up with multiple versions of the same file, which is not what I want. Is there a way to turn off this automatic appending of sequential numbers?