Capybara fill_in number field

I have a rails app that I am testing using capybara. I am currently testing the form for creating a system. I can get the fill in method to work for text fields but I cant get it to work for number fields how can I accomplish this?

This is what i have tried: describe "manage systems" do

    it "adds a new system and displays the results"do 

        visit '/systems/new'

        fill_in 'name', with: "test system"
        fill_in 'responsible_personnel', with: " John"
        find_by_id('status').find("option[value='Unavailable']").click
        fill_in 'criticality', :with 1
    end
end

criticality is the number field that i am trying to test