How to call a helper from another helper?

The helpers which export functions are quite easy to import and use inside another helper. I can do this:

import { startCase } from '<project-name>/helpers/start-case';

But there are some helpers which are exported only as Ember.Helper.helper. Normally those helpers are exported as default, so I import them like this:

import pluralize from '<project-name>/helpers/pluralize';

But I get Object is not a function error when I try to call pluralize. How can I call an imported Ember.Helper.helper object from inside another helper?