diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,16 @@
 # Revsion history of io-classes
 
+## next release
+
+### Breaking changes
+
+### Non-breaking changes
+
+## 1.3.0.0
+
+- `io-sim-1.3.0.0`.
+* Support `ghc-9.8`.
+
 ## 1.2.0.0
 
 ### Non-breaking changes
@@ -8,6 +19,7 @@
   an `MVar` in an underlying monad (if applicable). This is mainly useful for
   `io-sim`, since the underlying monad is `ST`. `IO` has no underlying monad, so
   the provided instance for `IO` defaults `inspectMVar` to `tryReadMVar`.
+* Add some Haddock documentation to `MonadDelay`
 
 ## 1.1.0.0
 
diff --git a/io-classes.cabal b/io-classes.cabal
--- a/io-classes.cabal
+++ b/io-classes.cabal
@@ -1,6 +1,6 @@
 cabal-version:       3.0
 name:                io-classes
-version:             1.2.0.0
+version:             1.3.0.0
 synopsis:            Type classes for concurrency with STM, ST and timing
 description:
   IO Monad class hierarchy compatible with
@@ -15,7 +15,7 @@
 build-type:          Simple
 extra-doc-files:     CHANGELOG.md README.md
 bug-reports:         https://github.com/input-output-hk/io-sim/issues
-tested-with:         GHC == { 8.10, 9.2, 9.4, 9.6 }
+tested-with:         GHC == { 8.10, 9.2, 9.4, 9.6, 9.8 }
 
 source-repository head
   type:     git
@@ -89,7 +89,7 @@
                        TypeFamilyDependencies
                        TypeOperators
                        UndecidableInstances
-  build-depends:       base  >=4.9 && <4.19,
+  build-depends:       base  >=4.9 && <4.20,
                        array,
                        async >=2.1,
                        bytestring,
diff --git a/src/Control/Monad/Class/MonadTimer.hs b/src/Control/Monad/Class/MonadTimer.hs
--- a/src/Control/Monad/Class/MonadTimer.hs
+++ b/src/Control/Monad/Class/MonadTimer.hs
@@ -4,6 +4,7 @@
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeFamilies        #-}
 
+-- | Provides classes to handle delays and timeouts.
 module Control.Monad.Class.MonadTimer
   ( MonadDelay (..)
   , MonadTimer (..)
@@ -18,13 +19,22 @@
 
 import qualified System.Timeout as IO
 
+-- | A typeclass to delay current thread.
 class Monad m => MonadDelay m where
+
+  -- | Suspends the current thread for a given number of microseconds
+  -- (GHC only).
+  --
+  -- See `IO.threadDelay`.
   threadDelay :: Int -> m ()
 
+-- | A typeclass providing utilities for /timeouts/.
 class (MonadDelay m, MonadSTM m) => MonadTimer m where
 
+  -- | See `STM.registerDelay`.
   registerDelay :: Int -> m (TVar m Bool)
 
+  -- | See `IO.timeout`.
   timeout :: Int -> m a -> m (Maybe a)
 
 --