diff --git a/Gemfile b/Gemfile
index a2eee99..df979dd 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,6 +3,7 @@ source "http://rubygems.org/"
 gem "bundler", "~> 1.1.rc.7"
 gem "rake", ">= 0.9.2.2"
 
+gem "test-unit", ">= 1", "< 2"
 gem "rspec"
 gem "require_all"
 gem "constructor"