diff --git a/src/lib/Witch/Instances.hs b/src/lib/Witch/Instances.hs
index 2ca9298..1273d09 100644
--- a/src/lib/Witch/Instances.hs
+++ b/src/lib/Witch/Instances.hs
@@ -8,6 +8,9 @@
 module Witch.Instances where
 
 import qualified Data.Bits as Bits
+import qualified Data.ByteString as ByteString
+import qualified Data.ByteString.Lazy as LazyByteString
+import qualified Data.ByteString.Short as ShortByteString
 import qualified Data.Complex as Complex
 import qualified Data.Fixed as Fixed
 import qualified Data.Foldable as Foldable
@@ -724,6 +727,42 @@ instance Cast.Cast [a] (Seq.Seq a) where
 instance Cast.Cast (Seq.Seq a) [a] where
   cast = Foldable.toList
 
+-- ByteString
+
+instance Cast.Cast [Word.Word8] ByteString.ByteString where
+  cast = ByteString.pack
+
+instance Cast.Cast ByteString.ByteString [Word.Word8] where
+  cast = ByteString.unpack
+
+instance Cast.Cast ByteString.ByteString LazyByteString.ByteString where
+  cast = LazyByteString.fromStrict
+
+instance Cast.Cast ByteString.ByteString ShortByteString.ShortByteString where
+  cast = ShortByteString.toShort
+
+-- LazyByteString
+
+instance Cast.Cast [Word.Word8] LazyByteString.ByteString where
+  cast = LazyByteString.pack
+
+instance Cast.Cast LazyByteString.ByteString [Word.Word8] where
+  cast = LazyByteString.unpack
+
+instance Cast.Cast LazyByteString.ByteString ByteString.ByteString where
+  cast = LazyByteString.toStrict
+
+-- ShortByteString
+
+instance Cast.Cast [Word.Word8] ShortByteString.ShortByteString where
+  cast = ShortByteString.pack
+
+instance Cast.Cast ShortByteString.ShortByteString [Word.Word8] where
+  cast = ShortByteString.unpack
+
+instance Cast.Cast ShortByteString.ShortByteString ByteString.ByteString where
+  cast = ShortByteString.fromShort
+
 fromNonNegativeIntegral :: (Integral s, Num t) => s -> Maybe t
 fromNonNegativeIntegral x = if x < 0 then Nothing else Just $ fromIntegral x
 
diff --git a/src/test/Main.hs b/src/test/Main.hs
index 392f705..b166372 100644
--- a/src/test/Main.hs
+++ b/src/test/Main.hs
@@ -5,6 +5,9 @@
 
 import qualified Control.Exception as Exception
 import qualified Control.Monad as Monad
+import qualified Data.ByteString as ByteString
+import qualified Data.ByteString.Lazy as LazyByteString
+import qualified Data.ByteString.Short as ShortByteString
 import qualified Data.Complex as Complex
 import qualified Data.Either as Either
 import qualified Data.Fixed as Fixed
@@ -1498,6 +1501,72 @@ main = Hspec.hspec . Hspec.describe "Witch" $ do
       test $ f (Seq.fromList [1]) `Hspec.shouldBe` [1]
       test $ f (Seq.fromList [1, 2]) `Hspec.shouldBe` [1, 2]
 
+    -- ByteString
+
+    Hspec.describe "Cast [Word8] ByteString" $ do
+      let f = Witch.cast @[Word.Word8] @ByteString.ByteString
+      test $ f [] `Hspec.shouldBe` ByteString.pack []
+      test $ f [0x00] `Hspec.shouldBe` ByteString.pack [0x00]
+      test $ f [0x0f, 0xf0] `Hspec.shouldBe` ByteString.pack [0x0f, 0xf0]
+
+    Hspec.describe "Cast ByteString [Word8]" $ do
+      let f = Witch.cast @ByteString.ByteString @[Word.Word8]
+      test $ f (ByteString.pack []) `Hspec.shouldBe` []
+      test $ f (ByteString.pack [0x00]) `Hspec.shouldBe` [0x00]
+      test $ f (ByteString.pack [0x0f, 0xf0]) `Hspec.shouldBe` [0x0f, 0xf0]
+
+    Hspec.describe "Cast ByteString LazyByteString" $ do
+      let f = Witch.cast @ByteString.ByteString @LazyByteString.ByteString
+      test $ f (ByteString.pack []) `Hspec.shouldBe` LazyByteString.pack []
+      test $ f (ByteString.pack [0x00]) `Hspec.shouldBe` LazyByteString.pack [0x00]
+      test $ f (ByteString.pack [0x0f, 0xf0]) `Hspec.shouldBe` LazyByteString.pack [0x0f, 0xf0]
+
+    Hspec.describe "Cast ByteString ShortByteString" $ do
+      let f = Witch.cast @ByteString.ByteString @ShortByteString.ShortByteString
+      test $ f (ByteString.pack []) `Hspec.shouldBe` ShortByteString.pack []
+      test $ f (ByteString.pack [0x00]) `Hspec.shouldBe` ShortByteString.pack [0x00]
+      test $ f (ByteString.pack [0x0f, 0xf0]) `Hspec.shouldBe` ShortByteString.pack [0x0f, 0xf0]
+
+    -- LazyByteString
+
+    Hspec.describe "Cast [Word8] LazyByteString" $ do
+      let f = Witch.cast @[Word.Word8] @LazyByteString.ByteString
+      test $ f [] `Hspec.shouldBe` LazyByteString.pack []
+      test $ f [0x00] `Hspec.shouldBe` LazyByteString.pack [0x00]
+      test $ f [0x0f, 0xf0] `Hspec.shouldBe` LazyByteString.pack [0x0f, 0xf0]
+
+    Hspec.describe "Cast LazyByteString [Word8]" $ do
+      let f = Witch.cast @LazyByteString.ByteString @[Word.Word8]
+      test $ f (LazyByteString.pack []) `Hspec.shouldBe` []
+      test $ f (LazyByteString.pack [0x00]) `Hspec.shouldBe` [0x00]
+      test $ f (LazyByteString.pack [0x0f, 0xf0]) `Hspec.shouldBe` [0x0f, 0xf0]
+
+    Hspec.describe "Cast LazyByteString ByteString" $ do
+      let f = Witch.cast @LazyByteString.ByteString @ByteString.ByteString
+      test $ f (LazyByteString.pack []) `Hspec.shouldBe` ByteString.pack []
+      test $ f (LazyByteString.pack [0x00]) `Hspec.shouldBe` ByteString.pack [0x00]
+      test $ f (LazyByteString.pack [0x0f, 0xf0]) `Hspec.shouldBe` ByteString.pack [0x0f, 0xf0]
+
+    -- ShortByteString
+
+    Hspec.describe "Cast [Word8] ShortByteString" $ do
+      let f = Witch.cast @[Word.Word8] @ShortByteString.ShortByteString
+      test $ f [] `Hspec.shouldBe` ShortByteString.pack []
+      test $ f [0x00] `Hspec.shouldBe` ShortByteString.pack [0x00]
+      test $ f [0x0f, 0xf0] `Hspec.shouldBe` ShortByteString.pack [0x0f, 0xf0]
+
+    Hspec.describe "Cast ShortByteString [Word8]" $ do
+      let f = Witch.cast @ShortByteString.ShortByteString @[Word.Word8]
+      test $ f (ShortByteString.pack []) `Hspec.shouldBe` []
+      test $ f (ShortByteString.pack [0x00]) `Hspec.shouldBe` [0x00]
+      test $ f (ShortByteString.pack [0x0f, 0xf0]) `Hspec.shouldBe` [0x0f, 0xf0]
+
+    Hspec.describe "Cast ShortByteString ByteString" $ do
+      let f = Witch.cast @ShortByteString.ShortByteString @ByteString.ByteString
+      test $ f (ShortByteString.pack []) `Hspec.shouldBe` ByteString.pack []
+      test $ f (ShortByteString.pack [0x00]) `Hspec.shouldBe` ByteString.pack [0x00]
+      test $ f (ShortByteString.pack [0x0f, 0xf0]) `Hspec.shouldBe` ByteString.pack [0x0f, 0xf0]
+
 test :: Hspec.Example a => a -> Hspec.SpecWith (Hspec.Arg a)
 test = Hspec.it ""
 
diff --git a/witch.cabal b/witch.cabal
index 44f409c..2f11f40 100644
--- a/witch.cabal
+++ b/witch.cabal
@@ -19,6 +19,7 @@ source-repository head
 common basics
   build-depends:
     , base >= 4.13.0 && < 4.16
+    , bytestring >= 0.10.12 && < 0.11
     , containers >= 0.6.2 && < 0.7
   default-language: Haskell2010
   ghc-options: