diff --git a/lib/ahoy_email.rb b/lib/ahoy_email.rb
index <HASH>..<HASH> 100644
--- a/lib/ahoy_email.rb
+++ b/lib/ahoy_email.rb
@@ -75,5 +75,5 @@ end
 ActiveSupport.on_load(:action_mailer) do
   include AhoyEmail::Mailer
   register_observer AhoyEmail::Observer
-  Mail::Message.attr_accessor :ahoy_data, :ahoy_message
+  Mail::Message.send(:attr_accessor, :ahoy_data, :ahoy_message)
 end
Fixed error with attr_accessor being private in earlier versions of Ruby - fixes #<I>