diff --git a/ConstraintKinds.cabal b/ConstraintKinds.cabal
--- a/ConstraintKinds.cabal
+++ b/ConstraintKinds.cabal
@@ -1,5 +1,5 @@
 Name:                ConstraintKinds
-Version:             0.0.1.1
+Version:             0.0.1.2
 Synopsis:            Repackages standard type classes with the ConstraintKinds extension
 Description:         This module provides more flexible versions of common type classes that use the ConstraintKinds extension.  This allows us to make types that require constraints instances of the popular classes.  For example, we reimplement Functor and Foldable using the ContraintKinds style.  This allows us to manipulate lists and unboxed vectors using the same functions.
                      .
diff --git a/src/Control/ConstraintKinds/Functor.hs b/src/Control/ConstraintKinds/Functor.hs
--- a/src/Control/ConstraintKinds/Functor.hs
+++ b/src/Control/ConstraintKinds/Functor.hs
@@ -20,7 +20,7 @@
 class Functor f where
     type FunctorConstraint f x :: Constraint
     type FunctorConstraint f x = ()
-
+    
     fmap :: (FunctorConstraint f a, FunctorConstraint f b) => (a -> b) -> f a -> f b
 
 -- | An infix synonym for 'fmap'.
@@ -31,6 +31,7 @@
 -- Instances
 
 instance Functor [] where
+    type FunctorConstraint [] x = ()
     {-# INLINE fmap #-}
     fmap = P.map
 
diff --git a/src/Control/ConstraintKinds/Traversable.hs b/src/Control/ConstraintKinds/Traversable.hs
--- a/src/Control/ConstraintKinds/Traversable.hs
+++ b/src/Control/ConstraintKinds/Traversable.hs
@@ -48,6 +48,7 @@
 -- instances
 
 instance Traversable [] where
+    type TraversableConstraint [] x = ()
     {-# INLINE traverse #-} -- so that traverse can fuse
     traverse f = Prelude.foldr cons_f (pure [])
       where cons_f x ys = (:) <$> f x <*> ys