diff --git a/ember-cli-rails.gemspec b/ember-cli-rails.gemspec
index ae6c6816..4c81e5e7 100644
--- a/ember-cli-rails.gemspec
+++ b/ember-cli-rails.gemspec
@@ -17,6 +17,7 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency "ember-cli-rails-assets", ">= 0.6.2", "< 1.0"
   spec.add_dependency "railties", ">= 4.2"
+  spec.add_dependency "rack", ">= 2.1", "< 4.0"
   spec.add_dependency "terrapin", "~> 0.6.0"
   spec.add_dependency "html_page", "~> 0.1.0"