diff --git a/test/support/rails_app.rb b/test/support/rails_app.rb
index 718face6..5f81d434 100644
--- a/test/support/rails_app.rb
+++ b/test/support/rails_app.rb
@@ -9,6 +9,10 @@ module ActiveModelSerializers
       config.action_controller.perform_caching = true
       config.action_controller.cache_store = :memory_store
 
+      if Rails::VERSION::MAJOR >= 6
+        config.action_dispatch.return_only_media_type_on_content_type = true
+      end
+
       config.filter_parameters += [:password]
     end