diff --git a/mixed-types-num.cabal b/mixed-types-num.cabal
--- a/mixed-types-num.cabal
+++ b/mixed-types-num.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: c571e2a889134066ae334e92527480bdc09db3eb49d6461c334c9184aa34be43
+-- hash: 3aadc479d775f322f55525a75972a2550f7039783922118344addf7514671100
 
 name:           mixed-types-num
-version:        0.5.0.1
+version:        0.5.0.2
 synopsis:       Alternative Prelude with numeric and logic expressions typed bottom-up
 description:    Please see the README on GitHub at <https://github.com/michalkonecny/mixed-types-num#readme>
 category:       Math
diff --git a/src/Numeric/MixedTypes/Kleenean.hs b/src/Numeric/MixedTypes/Kleenean.hs
--- a/src/Numeric/MixedTypes/Kleenean.hs
+++ b/src/Numeric/MixedTypes/Kleenean.hs
@@ -1,4 +1,5 @@
 {-# OPTIONS_GHC -Wno-orphans #-}
+{-# LANGUAGE DeriveGeneric #-}
 {-|
     Module      :  Numeric.MixedType.Kleenean
     Description :  Three-valued logic
@@ -12,15 +13,18 @@
 -}
 module Numeric.MixedTypes.Kleenean
 (
-    Kleenean(..), kleenean
+    Kleenean(..), kleenean, tKleenean
 )
 where
 
 import Numeric.MixedTypes.PreludeHiding
 import qualified Prelude as P
 
+import Test.SmallCheck.Series
+import GHC.Generics
+
 import Numeric.MixedTypes.Literals
-    ( ConvertibleExactly(..), convertExactly )
+    ( ConvertibleExactly(..), convertExactly, T(T) )
 import Numeric.MixedTypes.Bool
     ( (&&),
       not,
@@ -29,8 +33,13 @@
       CanTestCertainly(..),
       and )
 
+tKleenean :: T Kleenean
+tKleenean = T "Kleenean"
+
 data Kleenean = CertainTrue | CertainFalse | TrueOrFalse
-  deriving (P.Eq, Show)
+  deriving (P.Eq, Show, Generic)
+
+instance Serial IO Kleenean
 
 type CanBeKleenean t = ConvertibleExactly t Kleenean
 kleenean :: (CanBeKleenean t) => t -> Kleenean
diff --git a/test/Numeric/MixedTypes/BoolSpec.hs b/test/Numeric/MixedTypes/BoolSpec.hs
--- a/test/Numeric/MixedTypes/BoolSpec.hs
+++ b/test/Numeric/MixedTypes/BoolSpec.hs
@@ -18,21 +18,15 @@
 spec :: Spec
 spec = do
   specIsBool tBool
-  specIsBool tMaybeBool
-  specIsBool tMaybeMaybeBool
+  specIsBool tKleenean
   -- mixed-type tests:
-  specCanAndOr tBool tMaybeBool tBool
-  specCanAndOr tMaybeMaybeBool tMaybeBool tBool
-  describe "mixed-type Boolean operation examples" $ do
-    it "can do True || Just False" $ do
-      True || Just False `shouldBe` Just True
-    it "can do True || Nothing" $ do
-      True || (Nothing :: Maybe Bool) `shouldBe` Just True
-    it "can do Nothing || True" $ do
-      (Nothing :: Maybe Bool) || True `shouldBe` Just True
-    it "can do True || Just (Just False)" $ do
-      True || Just (Just False) `shouldBe` Just (Just True)
-    it "can do True || Just Nothing" $ do
-      True || Just (Nothing :: Maybe Bool) `shouldBe` Just (Just True)
-    it "can do Just Nothing || True" $ do
-      Just (Nothing :: Maybe Bool) || True `shouldBe` Just (Just True)
+  specCanAndOr tBool tKleenean tBool
+  -- describe "mixed-type Boolean operation examples" $ do
+  --   it "can do True || Nothing" $ do
+  --     True || (Nothing :: Maybe Bool) `shouldBe` Just True
+  --   it "can do Nothing || True" $ do
+  --     (Nothing :: Maybe Bool) || True `shouldBe` Just True
+  --   it "can do True || Just Nothing" $ do
+  --     True || Just (Nothing :: Maybe Bool) `shouldBe` Just (Just True)
+  --   it "can do Just Nothing || True" $ do
+  --     Just (Nothing :: Maybe Bool) || True `shouldBe` Just (Just True)