diff --git a/Data/ByteString/Internal/Pure.hs b/Data/ByteString/Internal/Pure.hs
index 33a931201..e13d6c3b7 100644
--- a/Data/ByteString/Internal/Pure.hs
+++ b/Data/ByteString/Internal/Pure.hs
@@ -28,7 +28,7 @@ where
 
 import Prelude
 
-import GHC.Exts                 (Char(..), indexCharOffAddr#, Ptr(..), ByteArray#, indexWord8Array#, Word8#, Int#, indexWord8OffAddr#)
+import GHC.Exts                 (Ptr(..), ByteArray#, indexWord8Array#, Word8#, Int#, indexWord8OffAddr#)
 import GHC.Types                (Int (..))
 import GHC.Word                 (Word8(..))
 import GHC.Int                  (Int8(..))
@@ -246,10 +246,10 @@ isValidUtf8' idx !len' = go 0
 ----------------------------------------------------------------
 
 
-getDigit :: Int -> Char
-getDigit (I# i) = C# (indexCharOffAddr# digits i)
+getDigit :: Int -> Word8
+getDigit (I# i) = W8# (indexWord8OffAddr# digits i)
   where
-    digits = "0123456789abcdef"#
+    !digits = "0123456789abcdef"#
 
 putDigit :: Ptr a -> Int -> Int -> IO ()
 putDigit !addr !off !i = pokeByteOff addr off (getDigit i)