Derive Generic for a data type that mentions a type synonym

Main.purs

module Main where
import Data.Generic

type Fields = {x :: String, y :: Int}

data WrappedFields = WrappedFields Fields

derive instance genericWF :: Generic WrappedFields

{-
Error message:
  No type class instance was found for

    Data.Generic.Generic { y :: Int
                         , x :: String
                         }


in value declaration genericWF

-}