diff --git a/actionmailer/lib/action_mailer/base.rb b/actionmailer/lib/action_mailer/base.rb
index e41c88d81bea7..ab616ebd84691 100644
--- a/actionmailer/lib/action_mailer/base.rb
+++ b/actionmailer/lib/action_mailer/base.rb
@@ -429,7 +429,7 @@ def deliver(mail)
       def register_template_extension(extension)
         ActiveSupport::Deprecation.warn(
           "ActionMailer::Base.register_template_extension has been deprecated." +
-          "Use ActionView::Base.register_template_extension instead", caller)
+          "Use ActionView::Template.register_template_handler instead", caller)
       end
 
       def template_root