How to wrap code examples in comments

Hi guys,
I'm new on documenting Ruby sources, I have some early opinions about
RDoc but this time and want to ask you something.
I tried to wrap code examples in comments using the following:
# <tt>
# def setUp
#     files << File.new()
# end
# </tt>

But it doesn't work, it generates an ugly HTML like
<tt> def setUp

    @appStates << AppState1.new()

end </tt>

What am I missing here?

Thanks,
Ubaldo