This is Phoebus's most recent tileset, as of the time of this writing, but I didn't like the new curved all pieces. Quiet honestly, they look mediocre for corners and look absolutely horrid for long diagonal sections. Meanwhile, the old style of angled walls looked good for single corners and looked absolutely fantastic for long diagonals! So I (got a friend of mine to) pluck the wall tiles off the old set and paste them into the new set. Since it's the same file name and dimensions, you just put this in your associated art folder and delete/rename/whatever the existing one!

(Maybe Phoebus will take a note here? Curved walls are cute, but after 5 minutes they start to become an eyesore....)