Simple, simple debug not working

[Jacob N.]

I'm trying to use Ruby's default, simple debugger but when I try to do a
"list" command from within the debugger, I get an error that states, "No
sourcefile available...".

For example:

hello.rb
===Contents===
require 'debug'

puts "Hello world"
========

~$ ruby hello.rb
===Output===
Debug.rb
Emacs support available.

hello.rb:4:
(rdb:1) l
[-1, 8] in hello.rb
No sourcefile available for hello.rb
(rdb:1)
========

I'm running Debian with C Ruby. I've also had this same issue on my
Gentoo box. I'd rather not install more programs and gems then
necessary.

I've searched all Google for a solution and have not found anything on
the subject. Thanks for any help you can provide!

~Jake