diff --git a/free-functors.cabal b/free-functors.cabal
--- a/free-functors.cabal
+++ b/free-functors.cabal
@@ -1,5 +1,5 @@
 name:                free-functors
-version:             0.1.1
+version:             0.1.2
 synopsis:            Provides free functors that are adjoint to functors that forget class constraints. 
 description:         A free functor is a left adjoint to a forgetful functor. It used to be the case
                      that the only category that was easy to work with in Haskell was Hask itself, so
@@ -43,7 +43,7 @@
     constraints >= 0.3.2 && < 0.4,
     transformers >= 0.2.0.0 && < 0.4,
     comonad >= 3.0 && < 3.1,
-    void >= 0.4 && < 0.6
+    void >= 0.4 && < 0.7
 
 source-repository head
   type:     git
diff --git a/src/Data/Functor/Free.hs b/src/Data/Functor/Free.hs
--- a/src/Data/Functor/Free.hs
+++ b/src/Data/Functor/Free.hs
@@ -22,7 +22,6 @@
 module Data.Functor.Free where
   
 import Control.Applicative
-import Control.Monad
 import Control.Comonad
 
 import Data.Constraint
@@ -89,5 +88,5 @@
 convert :: (c (f a), Applicative f) => Free c a -> f a
 convert = rightAdjunct pure
 
-convertClosed :: c x => Free c Void -> x
+convertClosed :: c r => Free c Void -> r
 convertClosed = rightAdjunct absurd