Decorators with babel, unexpected token

I'm trying to use decorators on classes in React, using babelify. I have the 'es7.decorators' option applied in babel, but I keep getting an 'unexpected token' error when it encounters the '@' character.

Anyone have any ideas? A simple example is below.

Decorator:

export default function(Component) {
  return class extends Component {
    constructor() {...}
  }
}

Class:

import myDecorator from 'decorator';

@myDecorator
class MyClass{...}

I'm using babelify (Browserify transform for Babel):

browserify().transform(babelify.configure({
  optional: ['es7.decorators']
})