diff --git a/src/UniqueLogic/ST/TF/Example/Label.hs b/src/UniqueLogic/ST/TF/Example/Label.hs
--- a/src/UniqueLogic/ST/TF/Example/Label.hs
+++ b/src/UniqueLogic/ST/TF/Example/Label.hs
@@ -14,7 +14,6 @@
 import Control.Monad.ST (ST, runST, )
 import Control.Monad (liftM2, liftM3, )
 
-import qualified Prelude as P
 import Prelude hiding (max, log)
 
 
diff --git a/src/UniqueLogic/ST/TF/Example/Rule.hs b/src/UniqueLogic/ST/TF/Example/Rule.hs
--- a/src/UniqueLogic/ST/TF/Example/Rule.hs
+++ b/src/UniqueLogic/ST/TF/Example/Rule.hs
@@ -8,7 +8,6 @@
 import Control.Monad.ST (runST, )
 import Control.Monad (liftM4, )
 
-import qualified Prelude as P
 import Prelude hiding (max)
 
 
diff --git a/src/UniqueLogic/ST/TF/Example/Verify.hs b/src/UniqueLogic/ST/TF/Example/Verify.hs
--- a/src/UniqueLogic/ST/TF/Example/Verify.hs
+++ b/src/UniqueLogic/ST/TF/Example/Verify.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE ExistentialQuantification #-}
 {-# LANGUAGE FlexibleInstances #-}
 module UniqueLogic.ST.TF.Example.Verify
 {-# WARNING "This module is intended for documentation purposes. Do not import it!" #-}
@@ -20,7 +21,6 @@
 import Control.Monad (liftM, liftM2, ap, when, )
 import Control.Applicative (Applicative, pure, (<*>), )
 
-import qualified Prelude as P
 import Prelude hiding (max, log)
 
 
diff --git a/src/UniqueLogic/ST/TF/System.hs b/src/UniqueLogic/ST/TF/System.hs
--- a/src/UniqueLogic/ST/TF/System.hs
+++ b/src/UniqueLogic/ST/TF/System.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE ExistentialQuantification #-}
 {-# LANGUAGE FlexibleInstances #-}
 module UniqueLogic.ST.TF.System (
    -- * Preparation
diff --git a/unique-logic-tf.cabal b/unique-logic-tf.cabal
--- a/unique-logic-tf.cabal
+++ b/unique-logic-tf.cabal
@@ -1,5 +1,5 @@
 Name:             unique-logic-tf
-Version:          0.4.1.1
+Version:          0.4.1.2
 License:          BSD3
 License-File:     LICENSE
 Author:           Henning Thielemann
@@ -64,7 +64,7 @@
 Build-Type:        Simple
 
 Source-Repository this
-  Tag:         0.4.1.1
+  Tag:         0.4.1.2
   Type:        darcs
   Location:    http://code.haskell.org/~thielema/unique-logic-tf/
 
@@ -75,7 +75,7 @@
 Library
   Build-Depends:
     explicit-exception >=0.1.7 && <0.2,
-    transformers >=0.2 && <0.4,
+    transformers >=0.2 && <0.5,
     containers >=0.4 && <0.6,
     utility-ht >=0.0.9 && <0.1,
     base >= 4 && <5
@@ -102,8 +102,8 @@
   GHC-Options: -Wall
   Build-Depends:
     unique-logic-tf,
-    QuickCheck >=2.4 && <2.6,
-    non-empty >=0.0 && <0.1,
+    QuickCheck >=2.4 && <3,
+    non-empty >=0.0 && <0.4,
     transformers,
     utility-ht,
     base