rvm rack ruby error already initialized constant WFKV_ [duplicate]

Possible Duplicate:

Rake “already initialized constant WFKV_” warning

I'm getting this error in my terminal when I use any ruby, rake or rails related commands. Commands are being executed and work fine, but before that I receive his error. Any suggestions? Thanks for advise开发者_如何学Go!

.rvm/gems/ruby-1.9.2-p290/gems/rack-1.3.4/lib/rack/backports/uri/common_192.rb:53: warning: already initialized constant WFKV_

I put gem 'rake', '1.3.3' in my Gemfile and ran bundle update rake and it works now.