If you modify any of the sass files currently, you get an error message like this:

```
Warning. Error encountered while saving cache _variables.sassc: can't dump anonymous class #<Class:0x007ffa80c8e150>
```

The fix is here:

http://stackoverflow.com/a/22287503/1780161

Basically, set back Sass to 3.2.13 until they fix this.