It doesn't work the way you'd think it would: Bundler disallows different versions for different platforms by design. When I add that and `bundle install` with Ruby 2.0.0 (and an empty `GEM_HOME` and no `Gemfile.lock`), it still resolves to `mime-types (1.25.1)`.

`gem 'mime-types', '~> 1.0' if RUBY_VERSION =~ /1.8.7/` does the trick, but I don't think it's a great idea to add conditionals in a `Gemfile`.

Is there a particular reason to prefer the newer version of `mime-types` on newer Ruby versions? I don't mean to be argumentative, just trying to understand. :smiley: