anchor.diff:  
           | Pattern.Character c ->
               // Make sure the character is an ASCII character unless the 'Unicode' option is set.
  -            if options.Unicode || int c <= 255 then
  +            if options.Unicode || int c <= int System.Byte.MaxValue then
                   return
                       Regex.ofChar c
                       |> Choice1Of2
  
positive.code:                 return err
              | Choice1Of2 r, Choice1Of2 s ->
                  return
                      Regex.And (r, s)
                      |> Choice1Of2
  
          | Pattern.Or (r, s) ->
  
negative.code:             // Make sure all of the characters in the set are ASCII characters unless the 'Unicode' option is set.
              if options.Unicode || CharSet.forall (fun c -> int c <= 255) charSet then
                  return
                      Regex.ofCharSet charSet
                      |> Choice1Of2
              else
                  return
  