From: Dean4Devil, https://github.com/Dean4Devil
Forwarded: https://github.com/mokus0/polynomial/pull/9

diff --git a/src/Data/VectorSpace/WrappedNum.hs b/src/Data/VectorSpace/WrappedNum.hs
index d7df2aa..271a4fb 100644
--- a/src/Data/VectorSpace/WrappedNum.hs
+++ b/src/Data/VectorSpace/WrappedNum.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE TemplateHaskell, TypeFamilies, MultiParamTypeClasses, FlexibleInstances, FlexibleContexts #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE RankNTypes #-}
 module Data.VectorSpace.WrappedNum
   (WrappedNum(..)) where
 
@@ -19,7 +20,7 @@ newtype WrappedNum a = WrapNum { unwrapNum :: a }
         , Floating, RealFloat)
 
 derivingUnbox "Wrapped"
-    [t| (U.Unbox a) => WrappedNum a -> a |] [| unwrapNum |] [| \ a -> WrapNum a |]
+    [t| forall a. (U.Unbox a) => WrappedNum a -> a |] [| unwrapNum |] [| \ a -> WrapNum a |]
 
 instance Num a => AdditiveGroup (WrappedNum a) where
     zeroV = 0