diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,7 @@
 # mixed-types-num change log
 
+* v 0.5.10 2022-07-13
+  * isValid and spec helpers for validity of operations
 * v 0.5.9 2021-08-04
   * compatible with ghc 9.0.1
   * separated module Mul from Ring
diff --git a/mixed-types-num.cabal b/mixed-types-num.cabal
--- a/mixed-types-num.cabal
+++ b/mixed-types-num.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           mixed-types-num
-version:        0.5.9.1
+version:        0.5.10
 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/Eq.hs b/src/Numeric/MixedTypes/Eq.hs
--- a/src/Numeric/MixedTypes/Eq.hs
+++ b/src/Numeric/MixedTypes/Eq.hs
@@ -23,6 +23,7 @@
   , specHasEq, specHasEqNotMixed
   , specConversion
   -- ** Specific comparisons
+  , CanTestValid(..), specResultIsValid1, specResultIsValid2, specResultIsValid1Pre, specResultIsValid2Pre
   , CanTestNaN(..)
   , CanTestFinite(..)
   , CanTestInteger(..)
@@ -254,7 +255,44 @@
   |]))
 
 
-{---- Checking whether it is finite -----}
+{---- Checking whether it is valid / finite -----}
+
+class CanTestValid t where
+  isValid :: t -> Bool
+
+{-|
+  HSpec property checking the validity of unary operations' results.
+ -}
+specResultIsValid1 ::
+  (Arbitrary t1, Show t1, CanTestValid t1, CanTestValid t2)
+  =>
+  (t1 -> t2) -> String -> T t1 -> Spec
+specResultIsValid1 = specResultIsValid1Pre (const True)
+
+specResultIsValid1Pre ::
+  (Arbitrary t1, Show t1, CanTestValid t1, CanTestValid t2)
+  =>
+  (t1 -> Bool) -> (t1 -> t2) -> String -> T t1 -> Spec
+specResultIsValid1Pre pre f fName (T tName1 :: T t1) =
+  it (printf "Function %s returns a valid result for valid %s inputs" fName tName1) $ do
+    property $ \ (x :: t1) -> isValid x && pre x ==> isValid (f x)
+
+{-|
+  HSpec properties that check validity of operations' results.
+ -}
+specResultIsValid2 ::
+  (Arbitrary t1, Show t1, Arbitrary t2, Show t2, CanTestValid t1, CanTestValid t2, CanTestValid t3)
+  =>
+  (t1 -> t2 -> t3) -> String -> T t1 -> T t2 -> Spec
+specResultIsValid2 = specResultIsValid2Pre (\_ _ -> True)
+
+specResultIsValid2Pre ::
+  (Arbitrary t1, Show t1, Arbitrary t2, Show t2, CanTestValid t1, CanTestValid t2, CanTestValid t3)
+  =>
+  (t1 -> t2 -> Bool) -> (t1 -> t2 -> t3) -> String -> T t1 -> T t2 -> Spec
+specResultIsValid2Pre pre f fName (T t1Name :: T t1) (T t2Name :: T t2) =
+  it (printf "Function %s returns a valid result for valid %s, %s inputs" fName t1Name t2Name) $ do
+    property $ \ (x :: t1) (y :: t2) -> isValid x && isValid y && pre x y ==> isValid (f x y)
 
 class CanTestNaN t where
   isNaN :: t -> Bool