1 files changed, 3 insertions, 1 deletions
diff --git a/actionview/lib/action_view/helpers/form_helper.rb b/actionview/lib/action_view/helpers/form_helper.rb
index 6d10b41bd5..c4371dc705 100644
--- a/actionview/lib/action_view/helpers/form_helper.rb
+++ b/actionview/lib/action_view/helpers/form_helper.rb
@@ -1935,6 +1935,8 @@ module ActionView
   end
 
   ActiveSupport.on_load(:action_view) do
-    cattr_accessor(:default_form_builder) { ::ActionView::Helpers::FormBuilder }
+    cattr_accessor(:default_form_builder, instance_writer: false, instance_reader: false) do
+      ::ActionView::Helpers::FormBuilder
+    end
   end
 end