diff --git a/hedgehog-extras.cabal b/hedgehog-extras.cabal
--- a/hedgehog-extras.cabal
+++ b/hedgehog-extras.cabal
@@ -1,7 +1,7 @@
 cabal-version: 2.4
 
 name:                   hedgehog-extras
-version:                0.4.3.0
+version:                0.4.4.1
 synopsis:               Supplemental library for hedgehog
 description:            Supplemental library for hedgehog.
 category:               Test
@@ -16,10 +16,10 @@
   type:                 git
   location:             https://github.com/input-output-hk/hedgehog-extras
 
-common aeson                        { build-depends: aeson                            >= 1.5.6.0                  }
+common aeson                        { build-depends: aeson                            >= 2.1.0.0                  }
 common aeson-pretty                 { build-depends: aeson-pretty                     >= 0.8.5                    }
 common async                        { build-depends: async                                                        }
-common base                         { build-depends: base                             >= 4.12       && < 4.17     }
+common base                         { build-depends: base                             >= 4.12       && < 4.19     }
 common bytestring                   { build-depends: bytestring                                                   }
 common deepseq                      { build-depends: deepseq                                                      }
 common Diff                         { build-depends: Diff                                                         }
diff --git a/src/Hedgehog/Extras/Stock/String.hs b/src/Hedgehog/Extras/Stock/String.hs
--- a/src/Hedgehog/Extras/Stock/String.hs
+++ b/src/Hedgehog/Extras/Stock/String.hs
@@ -2,11 +2,13 @@
   ( strip
   , lastLine
   , firstLine
-  , readM
+  , readNoteM
   ) where
 
 import           Control.Monad.Catch (MonadCatch)
+import           Data.Bifunctor
 import           Data.Function
+import           Data.Semigroup
 import           Data.String
 import           GHC.Stack
 import           Text.Read
@@ -17,7 +19,7 @@
 import qualified Hedgehog as H
 import qualified Hedgehog.Extras.Test.Base as H
 
--- | Strip whitepsace from the beginning and end of the string.
+-- | Strip whitespace from the beginning and end of the string.
 strip :: String -> String
 strip = T.unpack . T.strip . T.pack
 
@@ -29,6 +31,13 @@
 firstLine :: String -> String
 firstLine = strip . L.unlines . L.take 1 . L.lines
 
--- | Trim leading and trailing whitespace and read the string into a value
-readM :: (Read a, Show a, H.MonadTest m, MonadCatch m, HasCallStack) => String -> m a
-readM = withFrozenCallStack . H.noteShowM . H.evalEither . readEither . strip
+-- | Trim leading and trailing whitespace and read the string into a value. Report the read value in the test
+-- annotations.
+readNoteM :: (Read a, Show a, H.MonadTest m, MonadCatch m, HasCallStack) => String -> m a
+readNoteM inputStr =
+  withFrozenCallStack
+  $ H.noteShowM
+  . H.evalEither
+  . first (<> ": " <> inputStr)
+  . readEither
+  $ strip inputStr
diff --git a/src/Hedgehog/Extras/Stock/Time.hs b/src/Hedgehog/Extras/Stock/Time.hs
--- a/src/Hedgehog/Extras/Stock/Time.hs
+++ b/src/Hedgehog/Extras/Stock/Time.hs
@@ -6,7 +6,6 @@
   ) where
 
 import           Data.Int
-import           Data.Maybe
 import           Data.String
 import           Data.Time.Clock (UTCTime)
 import           Prelude (floor)
@@ -21,4 +20,4 @@
 
 -- | Format the given time as an ISO 8601 date-time string
 formatIso8601 :: UTCTime -> String
-formatIso8601 = DT.formatTime DT.defaultTimeLocale (DT.iso8601DateFormat (Just "%H:%M:%SZ"))
+formatIso8601 = DT.formatTime DT.defaultTimeLocale "%Y-%m-%dT%H:%M:%SZ"
diff --git a/src/Hedgehog/Extras/Test/Base.hs b/src/Hedgehog/Extras/Test/Base.hs
--- a/src/Hedgehog/Extras/Test/Base.hs
+++ b/src/Hedgehog/Extras/Test/Base.hs
@@ -52,6 +52,8 @@
   , assertByDeadlineIO
   , assertByDeadlineMFinally
   , assertByDeadlineIOFinally
+  , assertWith
+  , assertWithM
   , assertM
   , assertIO
   , assertWithinTolerance
@@ -452,6 +454,20 @@
         H.annotateShow currentTime
         g
         failMessage GHC.callStack "Condition not met by deadline"
+
+-- | Run the test function against the value. Report the value on the failure.
+assertWith :: (H.MonadTest m, Show p, HasCallStack) => p -> (p -> Bool) -> m ()
+assertWith v f = GHC.withFrozenCallStack $ assertWithM v (pure . f)
+
+-- | Run the test function against the value. Report the value on the failure.
+assertWithM :: (H.MonadTest m, Show p, HasCallStack) => p -> (p -> m Bool) -> m ()
+assertWithM v f = GHC.withFrozenCallStack $ do
+  result <- f v
+  if result
+     then H.success
+     else do
+       noteShow_ v
+       H.assert result
 
 -- | Run the monadic action 'f' and assert the return value is 'True'.
 assertM :: (MonadTest m, HasCallStack) => m Bool -> m ()