diff --git a/Data/Natural/Class.hs b/Data/Natural/Class.hs
deleted file mode 100644
--- a/Data/Natural/Class.hs
+++ /dev/null
@@ -1,12 +0,0 @@
-module Data.Natural.Class where
-
-import Data.Peano
-
-class Natural n where
-    natural :: f Zero -> (∀ m . Natural m => f (Succ m)) -> f n
-
-instance Natural Zero where
-    natural zf _ = zf
-
-instance Natural n => Natural (Succ n) where
-    natural _ sf = sf
diff --git a/natural-induction.cabal b/natural-induction.cabal
--- a/natural-induction.cabal
+++ b/natural-induction.cabal
@@ -1,5 +1,5 @@
 name:                natural-induction
-version:             0.1.0.0
+version:             0.1.0.1
 synopsis:            Induction over natural numbers
 -- description:         
 license:             BSD3
@@ -20,5 +20,6 @@
   default-language:    Haskell2010
   default-extensions:  UnicodeSyntax
                      , RankNTypes
+                     , PolyKinds
                      , DataKinds
   -- other-extensions: