[boost] [boost::asio] can't read into short streambuf

Hi boosters! I try to use asio::read_until() with a asio::streambuf of limited size and get the following error for sizes < 512: "boost::asio::streambuf too long" For sizes >= 512 everything works fine. Here is what I do: // create streambuf with max_size < 512 streambuf sbuf(100); // read into it ... read_until( socket, sbuf, expr, error_handler ); // throws here! What's wrong here? Cheers Sascha