Rails Zetwerk. How to load a file from a gem

Question

I have a helper module, and it uses a method located in a gem:

 include FontAwesome::Rails::IconHelper 

I'm getting the warning message:

  DEPRECATION WARNING: Initialization autoloaded the constant FontAwesome::Rails::IconHelper.

I tried including the gem in the file:

require 'font-awesome-rails'

But no success so far. How should I load the library using the correct way?