diff --git a/app/mailers/application_mailer.rb b/app/mailers/application_mailer.rb
index 8700d4539..a2612765e 100644
--- a/app/mailers/application_mailer.rb
+++ b/app/mailers/application_mailer.rb
@@ -1,4 +1,5 @@
 class ApplicationMailer < ActionMailer::Base
+  helper :application # gives access to all helpers defined within `application_helper`.
   default from: "demarches-simplifiees.fr <#{CONTACT_EMAIL}>"
   layout 'mailer'
 end