diff --git a/activemodel/Gemfile b/activemodel/Gemfile
index 289d696792..a192fdaf82 100644
--- a/activemodel/Gemfile
+++ b/activemodel/Gemfile
@@ -3,6 +3,7 @@ rails_root = Pathname.new(File.dirname(__FILE__)).join("..")
 Gem.sources.each { |uri| source uri }
 
 gem "activesupport", "3.0.pre", :vendored_at => rails_root.join("activesupport")
+gem "arel", :git => "git://github.com/rails/arel.git"
 
 only :test do
   gem "sqlite3-ruby"