zlib compression seems to decompress via gunzip but not curl

Question

I've written a http server that only sends back compressed http responses:

https://github.com/ericcurtin/asio/commit/1d37a1d225d1e812a747b595c02f9770ebd75dd0

So if you you use curl to request the data and decompress the response by piping through gunzip it works fine:

curl -x "" 127.0.0.1:5000/main.cpp --output - | gunzip
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   758  100   758    0     0   740k      0 --:--:-- --:--:-- --:--:--  740k
// g++ -O0 main.cpp server.cpp connection_manager.cpp request_handler.cpp
// connection.cpp reply.cpp mime_types.cpp request_parser.cpp -lboost_system
// -lpthread -lz
//
// run like: ./a.out 0.0.0.0 5000 .
//
// main.cpp
// ~~~~~~~~
//
// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#include <iostream>
#include <string>
#include <boost/asio.hpp>
#include "server.hpp"

int main(int argc, char* argv[])
{
  try
  {
    // Check command line arguments.
    if (argc != 4)
    {
      std::cerr << "Usage: http_server <address> <port> <doc_root>\n";
      std::cerr << "  For IPv4, try:\n";
      std::cerr << "    receiver 0.0.0.0 80 .\n";
      std::cerr << "  For IPv6, try:\n";
      std::cerr << "    receiver 0::0 80 .\n";
      return 1;
    }

    // Initialise the server.
    http::server::server s(argv[1], argv[2], argv[3]);

    // Run the server until stopped.
    s.run();
  }
  catch (std::exception& e)
  {
    std::cerr << "exception: " << e.what() << "\n";
  }

  return 0;
}

But if you use curl using --compressed which works with other http servers like the one at example.com it fails after the first 512 bytes:

curl -x "" 127.0.0.1:5000/main.cpp --compressed
// g++ -O0 main.cpp server.cpp connection_manager.cpp request_handler.cpp
// connection.cpp reply.cpp mime_types.cpp request_parser.cpp -lboost_system
// -lpthread -lz
//
// run like: ./a.out 0.0.0.0 5000 .
//
// main.cpp
// ~~~~~~~~
//
// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#include <iostream>
curl: (23) Failed writing received data to disk/application
#include <string

Any idea on how my compression could be fixed?