Am I allowed to fix bugs in tilesets?

I know we aren't allowed to change tilesets without the permission of the author, but is fixing a (little) bug also declared as a change?
In this case it's the "Cave ... thing by NeonPSY"-Tileset, which is very good but has that little bug, which sometimes really annoys me:

But you arent allowed to change tilesets without permission...so no?

You cannot modify the tileset in your game, but if you get permission from him, you could fix the bug and use your fixed tileset in your level.

Somepeople might rely on this bug, so fixing the source is not allowed (unless ofcource this tileset doesn't come with the game)

Somepeople might rely on this bug, so fixing the source is not allowed (unless ofcource this tileset doesn't come with the game)

Yeah, I know. If I would have fixed this bug, I would, ofcourse, include the tileset in my level. (I mean putting it into the tilesets folder of the level)

if you get permission from him, you could fix the bug

So... NeonPSY, am I allowed to fix this?