How to fix the deprecated Ember.Handlebars.registerBoundHelper in Ember 1.13.9?

I am currently upgrading from Ember 1.8.1 to Ember 1.13.9. My App is sort of oldschool by NOT using the ember-cli (no es6 whatever syntax).

How do i replace the deprecated Ember.Handlebars.registerBoundHelper properly:

Ember.Handlebars.registerBoundHelper('date-ago',function(date) {
  return moment.utc(date).fromNow();
});

will advice you to

DEPRECATION: `Ember.Handlebars.registerBoundHelper` is deprecated. 
Please refactor to use `Ember.Helpers.helper`. 
[deprecation id: ember-htmlbars.register-bound-helper]

So i thought replacing ´Ember.Handlebars.registerBoundHelper´ with ´Ember.Helper.helper´ would do, but then these helpers are not available any more: "Uncaught Error: Assertion Failed: A helper named 'date-ago' could not be found!".

How do I register a htmlbars helper in Ember 2.0 without ES6 syntax or ember-cli magic?