Getting Started Update Your Gemfile If you're using Rails, you'll need to change the required version of factory_girl_rails: gem "factory_girl_rails", "~> 4.0" If you're not using Rails, you'll just have to change the required version of factory_girl: gem "factory_girl", "~> 4.0" JRuby users: factory_girl works with JRuby starting with 1.6.7.2 (latest stable, as per July 2012). JRuby has to be use