diff --git a/Data/Type/Natural/Class/Arithmetic.hs b/Data/Type/Natural/Class/Arithmetic.hs
--- a/Data/Type/Natural/Class/Arithmetic.hs
+++ b/Data/Type/Natural/Class/Arithmetic.hs
@@ -115,7 +115,7 @@
                                         -> n :~: m
                 }
 
-class (SDecide nat, SNum nat, SEnum nat, nat ~ nat)
+class (SDecide nat, SNum nat, SEnum nat)
     => IsPeano nat where
   {-# MINIMAL succOneCong, succNonCyclic, predSucc, plusMinus,
               succInj, ( (plusZeroL, plusSuccL) | (plusZeroR, plusZeroL))
diff --git a/type-natural.cabal b/type-natural.cabal
--- a/type-natural.cabal
+++ b/type-natural.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                type-natural
-version:             0.7.1.0
+version:             0.7.1.1
 synopsis:            Type-level natural and proofs of their properties.
 description:         Type-level natural numbers and proofs of their properties.
                      .