diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog for the [`ghc-typelits-natnormalise`](http://hackage.haskell.org/package/ghc-typelits-natnormalise) package
 
+## 0.2.1 *May 6th 2015*
+* Update `Eq` instance of `SOP`: Empty SOP is equal to 0
+
 ## 0.2 *April 22nd 2015*
 * Finds more unifications:
   * `(2 + a) ~ 5  ==>  [a := 3]`
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,6 +1,8 @@
 # ghc-tynat-normalise
 
 [![Build Status](https://secure.travis-ci.org/christiaanb/ghc-typelits-natnormalise.png?branch=master)](http://travis-ci.org/christiaanb/ghc-typelits-natnormalise)
+[![Hackage](https://img.shields.io/hackage/v/ghc-typelits-natnormalise.svg)](https://hackage.haskell.org/package/ghc-typelits-natnormalise)
+[![Hackage Dependencies](https://img.shields.io/hackage-deps/v/ghc-typelits-natnormalise.svg?style=flat)](http://packdeps.haskellers.com/feed?needle=exact%3Aghc-typelits-natnormalise)
 
 A type checker plugin for GHC that can solve _equalities_ 
 of types of kind `Nat`, where these types are either:
diff --git a/ghc-typelits-natnormalise.cabal b/ghc-typelits-natnormalise.cabal
--- a/ghc-typelits-natnormalise.cabal
+++ b/ghc-typelits-natnormalise.cabal
@@ -1,5 +1,5 @@
 name:                ghc-typelits-natnormalise
-version:             0.2
+version:             0.2.1
 synopsis:            GHC typechecker plugin for types of kind GHC.TypeLits.Nat
 description:
   A type checker plugin for GHC that can solve /equalities/ of types of kind
diff --git a/src/GHC/TypeLits/Normalise/SOP.hs b/src/GHC/TypeLits/Normalise/SOP.hs
--- a/src/GHC/TypeLits/Normalise/SOP.hs
+++ b/src/GHC/TypeLits/Normalise/SOP.hs
@@ -105,7 +105,12 @@
   deriving (Eq,Ord)
 
 newtype SOP v c = S { unS :: [Product v c] }
-  deriving (Eq,Ord)
+  deriving (Ord)
+
+instance (Eq v, Eq c) => Eq (SOP v c) where
+  (S []) == (S [P [I 0]]) = True
+  (S [P [I 0]]) == (S []) = True
+  (S ps1) == (S ps2)      = ps1 == ps2
 
 instance (Outputable v, Outputable c) => Outputable (SOP v c) where
   ppr = hcat . punctuate (text " + ") . map ppr . unS