diff --git a/Acme/StrTok.hs b/Acme/StrTok.hs
--- a/Acme/StrTok.hs
+++ b/Acme/StrTok.hs
@@ -10,6 +10,7 @@
 @strTok@ is a stateful function (it produces different results when called with the same parameter multiple times), 
 computations using @strTok@ must take place in the @StrTok@ monad or the @StrTokT@ monad transformer.
 -}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 module Acme.StrTok (
     -- * The StrTokT monad transformer
     StrTokT,
@@ -23,8 +24,8 @@
 
 import Control.Applicative
 import Control.Monad
+import Control.Monad.State
 import Control.Monad.Identity
-import Control.Arrow
 import Control.Monad.Trans
 
 
@@ -33,41 +34,12 @@
 --   * @s@ - The type of list elements (e.g. @Char@ if the input to @strTok@ is a @String@).
 --
 --   * @m@ - The inner monad.
-newtype StrTokT s m a = StrTokT { runStrTokT' :: [s] -> m (a, [s]) }
-
-instance Functor m => Functor (StrTokT s m) where
-  fmap f (StrTokT g) = StrTokT $ fmap (first f) . g
-  
-instance (Functor m, Monad m) => Applicative (StrTokT s m) where
-  pure  = return
-  (<*>) = ap
-  
-instance (Functor m, MonadPlus m) => Alternative (StrTokT s m) where
-  empty = mzero
-  (<|>) = mplus
-    
-instance (MonadPlus m) => MonadPlus (StrTokT s m) where
-  mzero       = StrTokT $ const mzero
-  m `mplus` n = StrTokT $ \s -> runStrTokT' m s `mplus` runStrTokT' n s
-
-instance (MonadFix m) => MonadFix (StrTokT s m) where
-  mfix f = StrTokT $ \s -> mfix $ \ ~(a, _) -> runStrTokT' (f a) s   
-
-instance Monad m => Monad (StrTokT s m) where
-  return x = StrTokT $ \s -> return (x,s)
-  StrTokT f >>= g = StrTokT $ \s -> do {(x,s) <- f s; runStrTokT' (g x) s}
-
-instance MonadTrans (StrTokT s) where
-  lift m = StrTokT $ \s -> do {x <- m; return (x,s)}
-  
-instance (MonadIO m) => MonadIO (StrTokT s m) where
-    liftIO = lift . liftIO
+newtype StrTokT s m a = StrTokT (StateT [s] m a) 
+  deriving (Functor, Applicative, Alternative, Monad, MonadPlus, MonadFix, MonadTrans, MonadIO)
 
 -- | Executes a @strTok@ computation in the state transformer monad @StrTokT@.
 runStrTokT :: Functor m => StrTokT s m a -> m a
-runStrTokT (StrTokT f) = fmap fst (f [])
-
-
+runStrTokT (StrTokT x) = fmap fst (runStateT x [])
 
 -- | The @StrTok@ monad.
 type StrTok s = StrTokT s Identity
@@ -99,7 +71,7 @@
 --
 -- >("This","a"," sample string")
 strTok :: (Eq a, Monad m) => Maybe [a] -> [a] -> StrTokT a m [a]
-strTok s delims = StrTokT $ maybe strTok' (const . strTok') s
+strTok s delims = StrTokT $ StateT $ maybe strTok' (const . strTok') s
   where strTok' = return . break (`elem` delims) . dropWhile (`elem` delims)
 
 
diff --git a/acme-strtok.cabal b/acme-strtok.cabal
--- a/acme-strtok.cabal
+++ b/acme-strtok.cabal
@@ -10,7 +10,7 @@
 -- PVP summary:      +-+------- breaking API changes
 --                   | | +----- non-breaking API additions
 --                   | | | +--- code changes with no API change
-version:             0.1.0.2
+version:             0.1.0.3
 
 -- A short (one-line) description of the package.
 synopsis:            A Haskell port of the C/PHP strtok function