Rio and ruby 1.9

This week I am trying to move my development from ruby 1.8 to ruby 1.9
(ruby 1.9.1p243 (2009-07-16 revision 24175) [i686-linux]). I have pass
through most of the hurdles, but one I can not fix is ‘rio’ library. I
am using it extensively in my code. I am having following issue when I
do “require ‘rio’” in irb. Are there anybody who have fix this or can
point me what I need to do to fix this. Thanks.

/usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/base.rb:54: warning:
undefining object_id' may cause serious problem /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/base.rb:54: warning: undefiningsend’ may cause serious problem
NameError: uninitialized constant URI::REGEXP::PATTERN::PARAM
from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/uri/
file.rb:93:in <module:PATTERN>' from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/uri/ file.rb:88:inmodule:REGEXP
from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/uri/
file.rb:87:in <module:URI>' from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/uri/ file.rb:46:in<top (required)>’
from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/rl/
base.rb:39:in require' from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/rl/ base.rb:39:in<top (required)>’
from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/rl/
builder.rb:39:in require' from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/rl/ builder.rb:39:in<top (required)>’
from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/
factory.rb:45:in require' from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio/ factory.rb:45:in<top (required)>’
from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio.rb:56:in
require' from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio.rb:56:inclass:Rio
from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio.rb:53:in
<module:RIO>' from /usr/lib/ruby/gems/1.9.1/gems/rio-0.4.2/lib/rio.rb:52:in<top (required)>’
from (irb):1:in `require’
from (irb):1