File Output without frame number

Been held back from using File Output compositor nodes for a long time because they always append the frame number to the end of outputted files. A file with subpath "Grass ALB" is always exported as "Grass ALB0001.png"--as far as I know, there's no way to change it.

When I don't need animation (most of the time), this postfix actually prevents the Compositor from fitting neatly into my workflow. I'm often exporting multiple passes into a flat folder structure so they can be used by a game engine, and I need the files to follow an exact naming scheme. Having to delete the automatic frame postfix is extra cleanup work, and also physically prevents overwriting the destination files I'm trying to replace.

Having the option not to export the frame postfix in the first place would be a huge benefit.