ember-cli-eslint error build passes

In an Ember application, I'm trying to switch from jshint to eslint. I've followed the readme for http://ift.tt/29PCYek. Everything seems to work when I run "ember test", except when there is an eslint error the build will still pass. I see the eslint error in the console output, but the build will say "ok" when it is done and all the unit tests have passed. How do I get the build to fail if there is an eslint error?