Instead of setting enum _prefix to be working in my Rails 4 app, I've just done this in my User model instead: `enum otp_module: { otp_module_disabled: 0, otp_module_enabled: 1 }` Anyway, I think @Kobaltz's suggestion might be better.

Hi Guy! Thanks for this. It is cool. I can get it working with some pieces modification to where I can make/initial the QRCode worked. And, I'd just like to correct a wrong typo on your migration script as you have `rails g migraiton ...` and it should be `rails g migration ...`.