Map and terrain size mismatch help

I have a map with 64x64 grid squares, but I have a terrain tile set where each tile is 128x128. I’d like to be able to use the terrain tool with this terrain tile set, but when I try it treats the terrain like 64 x 64 instead of 128 x 128. Any way to make these play nice together?

Not until the following issue is resolved, which isn’t trivial:

Ah, alright. Thanks for the speedy response. I was hoping this might already be the case and I was just missing something, but apparently not.