Bundler could not find compatible versions for gem "mime-types"

I was going through my Gemfile updating to the latest releases when I got this error:

Bundler could not find compatible versions for gem "mime-types":
  In Gemfile:
    rails (= 4.0.2) ruby depends on
      mime-types (~> 1.16) ruby

    mechanize (= 2.7.3) ruby depends on
      mime-types (2.0)

Is it true that Rails 4.0.2 is depending on a much older version of mime-types than a lot of gems that are out there or is there something wrong with my local configuration?

P.S. I tried updating the dependencies with ´bundle update´, but I just got the same error again.