diff --git a/examples/safe-unsafe.hs b/examples/safe-unsafe.hs
--- a/examples/safe-unsafe.hs
+++ b/examples/safe-unsafe.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE FlexibleContexts, FlexibleInstances, UndecidableInstances #-}
+{-# LANGUAGE RankNTypes #-}
 module Main where
 import Data.Constraint.Unsafely
 import Data.IORef
diff --git a/src/Data/Constraint/Unsafely/Really.hs b/src/Data/Constraint/Unsafely/Really.hs
--- a/src/Data/Constraint/Unsafely/Really.hs
+++ b/src/Data/Constraint/Unsafely/Really.hs
@@ -1,5 +1,5 @@
-{-# LANGUAGE FlexibleContexts, FlexibleInstances, PolyKinds, RankNTypes #-}
-{-# LANGUAGE ScopedTypeVariables, UndecidableInstances                  #-}
+{-# LANGUAGE FlexibleInstances, PolyKinds, RankNTypes  #-}
+{-# LANGUAGE ScopedTypeVariables, UndecidableInstances #-}
 -- | Really unsafe module to provide internal interface.
 -- This module should be imported if you wish to allow the unsafe computation globally.
 --
@@ -8,7 +8,6 @@
 module Data.Constraint.Unsafely.Really (
   ReallyUnsafely, Unsafely, unsafely
   ) where
-import Data.Proxy
 import Unsafe.Coerce
 
 -- | The trick type-class to prevent providing global instances for @Unsafely@.
@@ -30,5 +29,5 @@
 newtype Thingy t a = Thingy (Unsafely t => a)
 
 -- | Evaluate the value which might be unsafe.
-unsafely :: forall t a. Proxy t -> (Unsafely t => a) -> a
+unsafely :: forall proxy t a. proxy t -> (Unsafely t => a) -> a
 unsafely _ f = unsafeCoerce (Thingy f :: Thingy t a) Impossible
diff --git a/unsafely.cabal b/unsafely.cabal
--- a/unsafely.cabal
+++ b/unsafely.cabal
@@ -1,5 +1,5 @@
 name:                unsafely
-version:             0.1.0.0.1
+version:             0.2.0.0
 synopsis:            Flexible access control for unsafe operations and instances
 description:         This module aims at providing simple interface to control the acccess for /unsafe/
                      operations and instance.
@@ -29,7 +29,7 @@
 library
   exposed-modules:     Data.Constraint.Unsafely, Data.Constraint.Unsafely.Really
   other-extensions:    FlexibleContexts, FlexibleInstances, RankNTypes, ScopedTypeVariables, UndecidableInstances
-  build-depends:       base >=4.6 && <4.7, tagged >=0.6 && <0.7
+  build-depends:       base >=4.6 && <4.8
   hs-source-dirs:      src
   default-language:    Haskell2010
 
@@ -38,7 +38,9 @@
     buildable:           True
   else
     buildable:           False
-  build-depends:       base >=4.6 && <4.7, tagged >=0.6 && <0.7, unsafely
+  build-depends:       base >=4.6 && <4.8, unsafely
+  if impl(ghc < 7.8)
+    build-depends:     tagged >=0.6 && <0.7
   hs-source-dirs:      examples
   main-is:             semigroup.hs
   default-language:    Haskell2010
@@ -48,7 +50,9 @@
     buildable:           True
   else
     buildable:           False
-  build-depends:       base >=4.6 && <4.7, tagged >=0.6 && <0.7, unsafely
+  build-depends:       base >=4.6 && <4.8, unsafely
+  if impl(ghc < 7.8)
+    build-depends:     tagged >=0.6 && <0.7
   hs-source-dirs:      examples
   main-is:             safe-unsafe.hs
   default-language:    Haskell2010