undefined method `bytesize' for #ActionDispatch::Response:0x000000042073b8

When processing a request, this error appears:

[2012-08-07 15:42:44] ERROR NoMethodError: undefined method `bytesize' for #<ActionDispatch::Response:0x000000042073b8>
/home/tbh/.rvm/gems/ruby-1.9.3-p125@skippr/gems/rack-mini-profiler-0.1.7/lib/mini_profiler/body_add_proxy.rb:18:in `method_missing'
/home/tbh/.rvm/gems/ruby-1.9.3-p125@skippr/gems/rack-1.2.5/lib/rack/utils.rb:276:in `bytesize'
/home/tbh/.rvm/gems/ruby-1.9.3-p125@skippr/gems/rack-1.2.5/lib/rack/content_length.rb:22:in `block i...
...

Using Rails 3.0.15, Ruby 1.9.3p125 Rack 1.2.5 rack-mini-profiler 0.1.7

This is way old, please grab the latest gem

Sorry, forgot to bundle update. Works fine, thanks!