diff --git a/isomorphism-class.cabal b/isomorphism-class.cabal
--- a/isomorphism-class.cabal
+++ b/isomorphism-class.cabal
@@ -1,6 +1,6 @@
 cabal-version: 3.0
 name: isomorphism-class
-version: 0.2.1
+version: 0.2.1.1
 synopsis: Lawful typeclasses for conversion between types
 category: Conversion
 homepage: https://github.com/nikita-volkov/isomorphism-class
diff --git a/library/IsomorphismClass/Classes/Is.hs b/library/IsomorphismClass/Classes/Is.hs
--- a/library/IsomorphismClass/Classes/Is.hs
+++ b/library/IsomorphismClass/Classes/Is.hs
@@ -28,6 +28,10 @@
 --
 -- For each pair of isomorphic types (/A/ and /B/) the compiler will require
 -- you to define four instances, namely: @Is A B@ and @Is B A@ as well as @IsSome A B@ and @IsSome B A@.
+--
+-- === Testing
+--
+-- For testing whether your instances conform to these laws use 'IsomorphismClass.isLawsProperties'.
 class (IsSome a b, Is b a) => Is a b
 
 -- | Any type is isomorphic to itself.