diff --git a/config/application.rb b/config/application.rb
index bed4e260..e6949ead 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -37,6 +37,8 @@ module Dawarich
 
     config.active_job.queue_adapter = :sidekiq
 
-    config.action_mailer.preview_paths << "#{Rails.root.join('spec/mailers/previews')}"
+    config.action_mailer.preview_paths << Rails.root.join('spec/mailers/previews').to_s
+
+    config.middleware.use Rack::Deflater
   end
 end