I receive this message when bundling using this example project: http://github.com/francois/rental_agency/tree/1ea252624e161ddc305a719d505a633d8d464e49 The included Gemfile references HEAD of rspec-core, and the gemspec there has this issue: Using rspec-core (2.0.0.beta.19) from git://github.com/rspec/rspec-core.git (at master) rspec-core at /Users/francois/.rvm/gems/ruby-1.9.2-rc2/bundler/gems/ rspec-core-3eb4494 did not have a valid gemspec. This prevents bundler from installing bins or native extensions, but that may not affect its functionality. The validation message from Rubygems was: ["lib/rspec/core/kernel_extensions.rb", "lib/rspec/core/ object_extensions.rb"] are not files I only had to refresh the gemspec in the rspec-core repository to fix this, which I''ve done here: http://github.com/francois/rspec-core/commit/52d08099a263f092423b58b1e9a9ed4e8589f7f8 Thanks! Fran?ois