Further backward compatability fix

Control/Monad/Trans/List.hs

@@ -146,7 +146,7 @@ instance (Monad m) => MonadPlus (ListT m) where
 instance (MonadFix m) => MonadFix (ListT m) where
     mfix f = ListT $ mfix (runListT . f . head) >>= \ xs -> case xs of
         [] -> return []
-        x:_ -> liftM (x:) (runListT (mfix (mapListT (fmap tail) . f)))
+        x:_ -> liftM (x:) (runListT (mfix (mapListT (liftM tail) . f)))
     {-# INLINE mfix #-}
 
 instance MonadTrans ListT where