Heroku push fails: Error: `libsass` bindings not found. Try reinstalling `node-sass`?

I'm trying to push a new app to Heroku but I'm getting this libsass error:

Error: ´libsass´ bindings not found. Try reinstalling ´node-sass´?

I've looked all around but the solutions I've found are for a local environment, but I have no problem on my machine.

One of the things I found was to use node 0.12.0, I was on 0.10, but Heroku is already on 0.12.0

What else can I do on Heroku?