diff --git a/Control/DeepSeq.hs b/Control/DeepSeq.hs
--- a/Control/DeepSeq.hs
+++ b/Control/DeepSeq.hs
@@ -3,9 +3,9 @@
 {-# LANGUAGE DefaultSignatures #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
-{-# LANGUAGE GADTs #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE Safe #-}
+{-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE PolyKinds #-}
 {-# LANGUAGE EmptyCase #-}
@@ -139,7 +139,7 @@
 #endif
 
 #if BYTEARRAY_IN_BASE
-import Data.Array.Byte (ByteArray(..))
+import Data.Array.Byte (ByteArray(..), MutableByteArray(..))
 #endif
 
 -- | Hidden internal type-class
@@ -152,9 +152,9 @@
 data Zero
 data One
 
-data RnfArgs arity a where
-  RnfArgs0 :: RnfArgs Zero a
-  RnfArgs1  :: (a -> ()) -> RnfArgs One a
+data family RnfArgs arity a
+data instance RnfArgs Zero a = RnfArgs0
+newtype instance RnfArgs One a = RnfArgs1 (a -> ())
 
 instance GNFData arity U1 where
   grnf _ U1 = ()
@@ -968,7 +968,11 @@
 -- ByteArray
 
 #if BYTEARRAY_IN_BASE
--- |@since 1.4.6.0
+-- |@since 1.4.7.0
 instance NFData ByteArray where
   rnf (ByteArray _) = ()
+
+-- |@since 1.4.8.0
+instance NFData (MutableByteArray s) where
+  rnf (MutableByteArray _) = ()
 #endif
diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,12 @@
 # Changelog for [`deepseq` package](http://hackage.haskell.org/package/deepseq)
 
+## 1.4.8.0
+
+  * Add `NFData` instance for `MutableByteArray`
+    ([#84](https://github.com/haskell/deepseq/pull/84))
+  * Change RnfArgs to be a data family
+    ([#85](https://github.com/haskell/deepseq/pull/85))
+
 ## 1.4.7.0
 
   * Add instances for `Solo` (GHC-9)
diff --git a/deepseq.cabal b/deepseq.cabal
--- a/deepseq.cabal
+++ b/deepseq.cabal
@@ -1,6 +1,6 @@
 cabal-version:  1.12
 name:           deepseq
-version:        1.4.7.0
+version:        1.4.8.0
 -- NOTE: Don't forget to update ./changelog.md
 
 license:        BSD3
@@ -59,7 +59,7 @@
   if impl(ghc >=9.0)
     build-depends: ghc-prim
 
-  build-depends: base       >= 4.9 && < 4.17,
+  build-depends: base       >= 4.9 && < 4.18,
                  array      >= 0.4 && < 0.6
   ghc-options: -Wall