Rails 3: uninitialized constant FactoryGirl

I am trying to create my first controller test using FactoryGirl for my Rails application, but I keep retrieving the following error: ``` uninitialized constant FactoryGirl ``` My Factories.rb file looks like this: ``` FactoryGirl.define do factory :offer, class: "Offer" do |f| f.title "Some title" f.description "SomeDescription" end end ``` And my controller test looks like this: ``` require 'spec_helper' describe OffersController do def valid_session {} end describe "GET index" do before { @offer = FactoryGirl.create(:offer) } it "assigns all offers as @offers" do get :index, {}, valid_session assigns(:offers).should eq([@offer]) end end end ``` My Gemfile looks like this: ``` group :development, :test do gem 'sqlite3' gem 'rspec-rails' gem 'capybara', '1.1.2' gem 'factory_girl_rails', '>= 4.1.0', :require => false end ``` What might I be missing since FactoryGirl isn't present?