diff --git a/dual.cabal b/dual.cabal
--- a/dual.cabal
+++ b/dual.cabal
@@ -1,5 +1,5 @@
 name:                dual
-version:             0.1.0.1
+version:             0.1.0.2
 synopsis:            Dual category
 -- description:         
 license:             BSD3
@@ -18,3 +18,4 @@
   build-depends:       base >=4.7 && <5
   -- hs-source-dirs:      
   default-language:    Haskell2010
+  default-extensions:  PolyKinds