I got Fixnum is deprecated when I ran Ruby project

When I run my project, i got these warning. Do you have any idea about that?

Thanks

It has more than 100 rows, i just added one.

C:/Ruby24-x64/lib/ruby/gems/2.4.0/gems/watir-webdriver-0.9.9/lib/watir-webdriver/elements/html_elements.rb:17: warning: constant ::Fixnum is deprecated