diff --git a/lib/prototype-rails/on_load_action_view.rb b/lib/prototype-rails/on_load_action_view.rb
index 2332d68..2f75b1e 100644
--- a/lib/prototype-rails/on_load_action_view.rb
+++ b/lib/prototype-rails/on_load_action_view.rb
@@ -13,10 +13,10 @@
   include ActionView::Helpers::PrototypeHelper
   include ActionView::Helpers::ScriptaculousHelper
 end
-
-ActionView::TestCase.class_eval do
-  include ActionView::Helpers::PrototypeHelper
-  include ActionView::Helpers::ScriptaculousHelper
+if ActionView::TestCase.present?
+  ActionView::TestCase.class_eval do
+    include ActionView::Helpers::PrototypeHelper
+    include ActionView::Helpers::ScriptaculousHelper
+  end
 end
-
 ActionView::Template.register_template_handler :rjs, ActionView::Template::Handlers::RJS.new