using Rails I18n in class

I have a class that generates PDF with Prawn:

class CustomersReport < Prawn::Document
  def to_pdf
    text "Hello, world"
    render
  end
end

How to use Rails I18n in this class? If I try to use translation() function, it prints u开发者_StackOverflow社区ndefined methodtranslation' for CustomersReport:Class`

I tried to add include ActionView::Helpers::TranslationHelperto my class, but no effect.

Use I18n.t(...) or I18n.translate(...).