diff --git a/base64.cabal b/base64.cabal
index bfeaca0..48c965e 100644
--- a/base64.cabal
+++ b/base64.cabal
@@ -25,6 +25,11 @@ source-repository head
   type:     git
   location: https://github.com/emilypi/base64.git
 
+flag simd
+  description: use libbase64 simd library
+  default: True
+  manual: True
+
 library
   exposed-modules:
     Data.Base64.Types
@@ -61,7 +66,13 @@ library
 
   hs-source-dirs:   src
   default-language: Haskell2010
-  ghc-options:      -Wall
+  ghc-options:      -Wall -O2
+
+  if flag(simd)
+    build-depends:
+      libbase64-bindings
+    cpp-options:
+      -DSIMD
 
 test-suite base64-tests
   default-language: Haskell2010
@@ -99,4 +110,4 @@ benchmark bench
     , random-bytestring
     , text               >=2.0
 
-  ghc-options:      -Wall -rtsopts
+  ghc-options:      -Wall -O2 -rtsopts
diff --git a/default.nix b/default.nix
index 700e928..aad3f2a 100644
--- a/default.nix
+++ b/default.nix
@@ -1,41 +1,47 @@
-{ nixpkgs ? import <nixpkgs> {}, compiler ? "default", doBenchmark ? false }:
-
 let
+  hs-libbase64 = import (builtins.fetchTarball {
+    url = "https://github.com/chessai/hs-libbase64-bindings/archive/e8a5194742f41ce4109b05098a2859e8052ad1c1.tar.gz";
+    sha256 = "1xqfjqb1ghh8idnindc6gfr62d78m5cc6jpbhv1hja8lkdrl8qf8";
+  }) {};
+in
+{
+  compiler ? "ghc944",
+  pkgs ? import <nixpkgs> {
+    config = {
+      allowBroken = false;
+      allowUnfree = false;
+    };
+
+    overlays = [ ];
+      /*(self: super: {
+        # not in nixpkgs yet
+        inherit (hs-libbase64) libbase64;
+
+        "haskell.packages.${compiler}" = haskell.packages.${compiler}.override {
+          overrides = hself: hsuper: {
+            inherit (hs-libbase64) libbase64-bindings;
+          };
+        };
+      })*/
+  },
+  returnShellEnv ? false,
+}:
 
-  inherit (nixpkgs) pkgs;
-
-  f = { mkDerivation, base, base64-bytestring, bytestring
-      , criterion, deepseq, ghc-byteorder, QuickCheck, random-bytestring
-      , stdenv, tasty, tasty-hunit, tasty-quickcheck, text, text-short
-      }:
-      mkDerivation {
-        pname = "base64";
-        version = "0.4.2.2";
-        src = ./.;
-        libraryHaskellDepends = [
-          base bytestring deepseq ghc-byteorder text text-short
-        ];
-        testHaskellDepends = [
-          base base64-bytestring bytestring QuickCheck random-bytestring
-          tasty tasty-hunit tasty-quickcheck text text-short
-        ];
-        benchmarkHaskellDepends = [
-          base base64-bytestring bytestring criterion deepseq
-          random-bytestring text
-        ];
-        homepage = "https://github.com/emilypi/base64";
-        description = "Fast RFC 4648-compliant Base64 encoding";
-        license = stdenv.lib.licenses.bsd3;
-      };
-
-  haskellPackages = if compiler == "default"
-                       then pkgs.haskellPackages
-                       else pkgs.haskell.packages.${compiler};
-
-  variant = if doBenchmark then pkgs.haskell.lib.doBenchmark else pkgs.lib.id;
-
-  drv = variant (haskellPackages.callPackage f {});
-
+let
+  nix-gitignore = import (pkgs.fetchFromGitHub {
+    owner = "hercules-ci";
+    repo = "gitignore";
+    rev = "9e80c4d83026fa6548bc53b1a6fab8549a6991f6";
+    sha256 = "04n9chlpbifgc5pa3zx6ff3rji9am6msrbn1z3x1iinjz2xjfp4p";
+  }) {};
 in
+pkgs.haskell.packages.${compiler}.developPackage {
+  name = "base64";
+  root = nix-gitignore.gitignoreSource ./.;
+
+  overrides = self: super: {
+    inherit (hs-libbase64) libbase64-bindings;
+  };
 
-  if pkgs.lib.inNixShell then drv.env else drv
+  inherit returnShellEnv;
+}
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..9d44e74
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1 @@
+import ./default.nix { returnShellEnv = true; }
diff --git a/src/Data/ByteString/Base64/Internal/Head.hs b/src/Data/ByteString/Base64/Internal/Head.hs
index 92db0c7..56f9c92 100644
--- a/src/Data/ByteString/Base64/Internal/Head.hs
+++ b/src/Data/ByteString/Base64/Internal/Head.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 -- |
 -- Module       : Data.ByteString.Base64.Internal.Head
 -- Copyright    : (c) 2019-2022 Emily Pillmore
@@ -35,9 +36,50 @@ import GHC.Word
 
 import System.IO.Unsafe ( unsafeDupablePerformIO )
 
+#ifdef SIMD
+import Foreign.C.Types (CChar, CInt, CSize)
+import Foreign.Storable (peek)
+import qualified Foreign.Marshal.Utils as Foreign
+import qualified Data.Text as T
+import LibBase64Bindings
+#endif
 
 encodeBase64_ :: EncodingTable -> ByteString -> ByteString
-encodeBase64_ (EncodingTable !aptr !efp) (PS !sfp !soff !slen) =
+#ifdef SIMD
+encodeBase64_ table b@(PS _ _ !slen)
+  | slen < threshold = encodeBase64Loop_ table b
+  | otherwise        = encodeBase64Simd_ b
+  where
+    !threshold = 1000 -- 1k
+#else
+encodeBase64_ table b = encodeBase64Loop_ table b
+#endif
+{-# inline encodeBase64_ #-}
+
+#ifdef SIMD
+encodeBase64Simd_ :: ByteString -> ByteString
+encodeBase64Simd_ (PS !sfp !soff !slen) =
+  unsafeDupablePerformIO $ do
+    dfp <- mallocPlainForeignPtrBytes dlen
+    dlenFinal <- do
+      withForeignPtr dfp $ \out ->
+        withForeignPtr sfp $ \src -> do
+          Foreign.with (intToCSize dlen) $ \outlen -> do
+            base64_encode
+              (plusPtr (castPtr src :: Ptr CChar) soff)
+              (intToCSize slen)
+              out
+              outlen
+              base64Flags
+            peek outlen
+    pure (PS (castForeignPtr dfp) 0 (cSizeToInt dlenFinal))
+  where
+    !dlen = 4 * ((slen + 2) `div` 3)
+    !base64Flags = 0
+#endif
+
+encodeBase64Loop_ :: EncodingTable -> ByteString -> ByteString
+encodeBase64Loop_ (EncodingTable !aptr !efp) (PS !sfp !soff !slen) =
     unsafeDupablePerformIO $ do
       dfp <- mallocPlainForeignPtrBytes dlen
       withForeignPtr dfp $ \dptr ->
@@ -70,6 +112,33 @@ encodeBase64Nopad_ (EncodingTable !aptr !efp) (PS !sfp !soff !slen) =
   where
     !dlen = 4 * ((slen + 2) `div` 3)
 
+#ifdef SIMD
+decodeBase64Simd_ :: ByteString -> IO (Either Text ByteString)
+decodeBase64Simd_ (PS !sfp !soff !slen) = do
+  withForeignPtr sfp $ \src -> do
+    dfp <- mallocPlainForeignPtrBytes dlen
+    edlenFinal :: Either Text CSize <- do
+      withForeignPtr dfp $ \out -> do
+        Foreign.with (intToCSize dlen) $ \outlen -> do
+          decodeResult <- base64_decode
+            (plusPtr (castPtr src :: Ptr CChar) soff)
+            (intToCSize slen)
+            out
+            outlen
+            base64Flags
+          case decodeResult of
+            1    -> Right <$> peek outlen
+            0    -> pure (Left "SIMD: Invalid input")
+            (-1) -> pure (Left "Invalid Codec")
+            x    -> pure (Left ("Unexpected result from libbase64 base64_decode: " <> T.pack (show (cIntToInt x))))
+    pure $ fmap
+      (\dlenFinal -> PS (castForeignPtr dfp) 0 (cSizeToInt dlenFinal))
+      edlenFinal
+  where
+    !dlen = (slen `quot` 4) * 3
+    !base64Flags = 0
+#endif
+
 -- | The main decode function. Takes a padding flag, a decoding table, and
 -- the input value, producing either an error string on the left, or a
 -- decoded value.
@@ -84,7 +153,22 @@ decodeBase64_
     :: ForeignPtr Word8
     -> ByteString
     -> IO (Either Text ByteString)
-decodeBase64_ !dtfp (PS !sfp !soff !slen) =
+#ifdef SIMD
+decodeBase64_ dtfp b@(PS _ _ !slen)
+  | slen < threshold = decodeBase64Loop_ dtfp b
+  | otherwise        = decodeBase64Simd_ b
+  where
+    !threshold = 250
+#else
+decodeBase64_ dtfp b = decodeBase64Loop_ dtfp b
+#endif
+{-# inline decodeBase64_ #-}
+
+decodeBase64Loop_
+    :: ForeignPtr Word8
+    -> ByteString
+    -> IO (Either Text ByteString)
+decodeBase64Loop_ !dtfp (PS !sfp !soff !slen) =
     withForeignPtr dtfp $ \dtable ->
     withForeignPtr sfp $ \sptr -> do
       dfp <- mallocPlainForeignPtrBytes dlen
@@ -95,7 +179,7 @@ decodeBase64_ !dtfp (PS !sfp !soff !slen) =
           dptr end dfp
   where
     !dlen = (slen `quot` 4) * 3
-{-# inline decodeBase64_ #-}
+{-# inline decodeBase64Loop_ #-}
 
 -- | The main decode function for typed base64 values.
 --
@@ -137,3 +221,14 @@ decodeBase64Lenient_ !dtfp (PS !sfp !soff !slen) = unsafeDupablePerformIO $
           dfp
   where
     !dlen = ((slen + 3) `div` 4) * 3
+
+#ifdef SIMD
+intToCSize :: Int -> CSize
+intToCSize = fromIntegral
+
+cSizeToInt :: CSize -> Int
+cSizeToInt = fromIntegral
+
+cIntToInt :: CInt -> Int
+cIntToInt = fromIntegral
+#endif