diff --git a/Gemfile b/Gemfile
index 8d0c75e..4458b38 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,4 +8,5 @@ group :development do
   gem "rake"
   gem "test-unit"
   gem "test-unit-ruby-core"
+  gem "irb"
 end