diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # lzlib
 
+## 0.3.1.2
+
+  * Hopefully improved performance
+
 ## 0.3.1.1
 
   * Bug fix + more sensible memory use
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright Vanessa McHale (c) 2019
+Copyright Vanessa McHale (c) 2019-2020
 
 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
 
diff --git a/lzlib.cabal b/lzlib.cabal
--- a/lzlib.cabal
+++ b/lzlib.cabal
@@ -1,9 +1,9 @@
 cabal-version:      1.18
 name:               lzlib
-version:            0.3.1.1
+version:            0.3.1.2
 license:            BSD3
 license-file:       LICENSE
-copyright:          Copyright: (c) 2019 Vanessa McHale
+copyright:          Copyright: (c) 2019-2020 Vanessa McHale
 maintainer:         vamchale@gmail.com
 author:             Vanessa McHale
 synopsis:           lzlib bindings
diff --git a/src/Codec/Lzip.hs b/src/Codec/Lzip.hs
--- a/src/Codec/Lzip.hs
+++ b/src/Codec/Lzip.hs
@@ -9,16 +9,17 @@
                   ) where
 
 import           Codec.Lzip.Raw
-import           Control.Exception     (bracket)
-import           Control.Monad         (void, when)
-import           Data.Bits             (shiftL)
-import qualified Data.ByteString       as BS
-import qualified Data.ByteString.Lazy  as BSL
-import           Data.Functor          (($>))
-import           Data.Int              (Int64)
-import           Foreign.Marshal.Alloc (free, mallocBytes)
-import           Foreign.Ptr           (Ptr, castPtr)
-import           System.IO.Unsafe      (unsafeDupablePerformIO)
+import           Control.Exception      (bracket)
+import           Control.Monad          (void, when)
+import           Data.Bits              (shiftL)
+import qualified Data.ByteString        as BS
+import qualified Data.ByteString.Lazy   as BSL
+import qualified Data.ByteString.Unsafe as BS
+import           Data.Functor           (($>))
+import           Data.Int               (Int64)
+import           Foreign.Marshal.Alloc  (free, mallocBytes)
+import           Foreign.Ptr            (Ptr, castPtr)
+import           System.IO.Unsafe       (unsafeDupablePerformIO)
 
 data CompressionLevel = Zero
                       | One
@@ -91,10 +92,10 @@
                 (bs':bss') -> if BS.length bs' > maxSz
                     then do
                         let (bs'', rest) = BS.splitAt maxSz bs'
-                        BS.useAsCStringLen bs'' $ \(bytes, sz) ->
+                        BS.unsafeUseAsCStringLen bs'' $ \(bytes, sz) ->
                             lZDecompressWrite decoder (castPtr bytes) (fromIntegral sz) $> rest:bss'
                     else
-                        BS.useAsCStringLen bs' $ \(bytes, sz) ->
+                        BS.unsafeUseAsCStringLen bs' $ \(bytes, sz) ->
                             lZDecompressWrite decoder (castPtr bytes) (fromIntegral sz) $>
                             bss'
                 [] -> pure []
@@ -140,10 +141,10 @@
         loop :: LZEncoderPtr -> [BS.ByteString] -> (Ptr UInt8, Int) -> Int -> [BS.ByteString] -> IO [BS.ByteString]
         loop encoder bss (buf, sz) bytesRead acc = do
             bss' <- case bss of
-                [bs] -> BS.useAsCStringLen bs $ \(bytes, sz') -> do
+                [bs] -> BS.unsafeUseAsCStringLen bs $ \(bytes, sz') -> do
                     void $ lZCompressWrite encoder (castPtr bytes) (fromIntegral sz')
                     lZCompressFinish encoder $> []
-                (bs:bss') -> BS.useAsCStringLen bs $ \(bytes, sz') ->
+                (bs:bss') -> BS.unsafeUseAsCStringLen bs $ \(bytes, sz') ->
                     lZCompressWrite encoder (castPtr bytes) (fromIntegral sz') $> bss'
                 [] -> pure []
             bytesActual <- lZCompressRead encoder buf (fromIntegral sz)