Pluralization translate fails

[hauleth]

I'm writeing my app with :pl locale and I've got custom plural method (because I must have one) that look like

def slavic(n)
  if n == 1
    :one
  elsif [2, 3, 4].include?(n % 10) and ![12, 13, 14, 22, 23, 24].include?(n % 100)
    :few
  else
    :other
  end
end

{
  pl: {
    i18n: {
      plural: {
        keys: [:one, :few, :other],
        rule: ->(n){ slavic n }
      }
    }
  }
}

But when I use CopyCopter and try to translate with t MyModel.model_name.human count: 2 it return :other key instead of :few.