diff --git a/monad-supply.cabal b/monad-supply.cabal
--- a/monad-supply.cabal
+++ b/monad-supply.cabal
@@ -1,6 +1,6 @@
 Name:          monad-supply
 Build-type:    Simple
-Version:       0.5
+Version:       0.6
 Cabal-Version: >= 1.6
 Synopsis:      Stateful supply monad.
 Description:   Support for computations which consume values from a (possibly infinite) supply.
diff --git a/src/Control/Monad/Supply.hs b/src/Control/Monad/Supply.hs
--- a/src/Control/Monad/Supply.hs
+++ b/src/Control/Monad/Supply.hs
@@ -21,7 +21,7 @@
 import Control.Applicative
 import Control.Monad.Identity
 import Control.Monad.State
-import Control.Monad.Except
+import Control.Monad.Error
 import Control.Monad.Reader
 import Control.Monad.Writer
 
@@ -46,7 +46,7 @@
   exhausted = SupplyT $ gets null
 
 -- Monad transformer instances
-instance MonadSupply s m => MonadSupply s (ExceptT e m) where
+instance (Error e,MonadSupply s m) => MonadSupply s (ErrorT e m) where
   supply = lift supply
   peek = lift peek
   exhausted = lift exhausted