Ember helper is not defined

I can't figure out why the helper I created in app/helpers/shop-name.js:

import { helper } from '@ember/component/helper';

export function shopName(shop) {
  return shop.identifier + '-' + shop.name;
}

export default helper(shopName);

is not available in my template application.hbs:

<select>
  
    <option value=></option>
  
</select>

I get the template compilation errors.

I'm using Ember 3.0. Thank you.