diff --git a/Data/ByteString/Internal/Pure.hs b/Data/ByteString/Internal/Pure.hs
index d04cb13b3..cf41dcb67 100644
--- a/Data/ByteString/Internal/Pure.hs
+++ b/Data/ByteString/Internal/Pure.hs
@@ -333,7 +333,7 @@ encodeUnsignedHex' !v !orig_ptr !next_ptr = do
     _ -> encodeUnsignedHex' q orig_ptr (plusPtr next_ptr 1)
 
 
-lower_hex_table :: Ptr ()
+lower_hex_table :: Ptr Word16
 lower_hex_table = Ptr
   "000102030405060708090a0b0c0d0e0f\
   \101112131415161718191a1b1c1d1e1f\