diff --git a/actionpack/lib/action_controller/metal/renderers.rb b/actionpack/lib/action_controller/metal/renderers.rb
index <HASH>..<HASH> 100644
--- a/actionpack/lib/action_controller/metal/renderers.rb
+++ b/actionpack/lib/action_controller/metal/renderers.rb
@@ -8,8 +8,7 @@ module ActionController
 
   class MissingRenderer < LoadError
     def initialize(format)
-      @format = format
-      super("No renderer defined for format: #{@format}")
+      super "No renderer defined for format: #{format}"
     end
   end
Do not use instance variables if they are not reused elsewhere