diff --git a/simulation/test_http_connection.cpp b/simulation/test_http_connection.cpp
index e961a3038..a4ef4a280 100644
--- a/simulation/test_http_connection.cpp
+++ b/simulation/test_http_connection.cpp
@@ -40,10 +40,14 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/aux_/proxy_settings.hpp"
 #include "libtorrent/http_connection.hpp"
 #include "libtorrent/resolver.hpp"
+#include "libtorrent/io.hpp"
+
+#include <boost/crc.hpp>
 
 using namespace libtorrent;
 using namespace sim;
 namespace lt = libtorrent;
+namespace io = lt::detail;
 
 using chrono::duration_cast;
 
@@ -174,6 +178,7 @@ enum expect_counters
 	rel_redirect_req = 4,
 	inf_redirect_req = 5,
 	chunked_req = 6,
+	test_file_gz_req = 7,
 
 	num_counters
 };
@@ -208,8 +213,10 @@ TORRENT_TEST(http_connection)
 	// make sure hostname lookup failures are passed through correctly
 	run_test("http://non-existent.com/test_file", 0, -1, asio::error::host_not_found, { 0, 1});
 
+	// make sure we handle gzipped content correctly
+	run_test(url_base + "/test_file.gz", 1337, 200, error_code(), { 1, 1, 0, 0, 0, 0, 0, 1});
+
 //	run_test(url_base + "/password_protected", 1337, 200, error_code(), { 1, 1, 1});
-//	run_test(url_base + "/test_file.gz", 1337, 200, error_code(), { 1, 1, 1});
 
 //#error test all proxies
 //#error test https
@@ -263,6 +270,39 @@ void run_test(std::string url, int expect_size, int expect_status
 			+ chunk_string(std::string(data_buffer, 1337));
 	});
 
+	http.register_handler("/test_file.gz"
+	, [data_buffer,&counters](std::string method, std::string req
+		, std::map<std::string, std::string>& headers)
+	{
+		++counters[test_file_gz_req];
+		print_http_header(headers);
+		TEST_EQUAL(method, "GET");
+
+		char const* extra_headers[4] = {"Content-Encoding: gzip\r\n", "", "", ""};
+		unsigned char const gzheader[] = {
+			0x1f , 0x8b , 0x08 , 0x00 // ID, compression=deflate, flags=0
+			, 0x00 , 0x00 , 0x00 , 0x00 // mtime=0
+			, 0x00, 0x01 // extra headers, OS
+			, 0x01 // last block, uncompressed
+			, 0x39 , 0x05, 0xc6 , 0xfa // length = 1337 (little endian 16 bit and inverted)
+		};
+		unsigned char trailer[8] = { 0, 0, 0, 0, 0x39, 0x05, 0x00, 0x00 };
+		boost::crc_32_type crc;
+		crc.process_bytes(data_buffer, 1337);
+		boost::uint32_t checksum = crc.checksum();
+		trailer[0] = checksum >> 24;
+		trailer[1] = (checksum >> 16) & 0xff;
+		trailer[2] = (checksum >> 8) & 0xff;
+		trailer[3] = (checksum) & 0xff;
+
+		std::string ret = sim::send_response(200, "OK", 1337 + sizeof(gzheader)
+			+ sizeof(trailer), extra_headers);
+		ret.append(std::string((char const*)gzheader, sizeof(gzheader)));
+		ret.append(data_buffer, 1337);
+		ret.append(std::string((char const*)trailer, sizeof(trailer)));
+		return ret;
+	});
+
 	http.register_handler("/redirect"
 		, [data_buffer,&counters](std::string method, std::string req
 		, std::map<std::string, std::string>& headers)
diff --git a/src/gzip.cpp b/src/gzip.cpp
index 99627c883..c262e6b23 100644
--- a/src/gzip.cpp
+++ b/src/gzip.cpp
@@ -119,6 +119,8 @@ namespace libtorrent
 		const unsigned char* buffer = reinterpret_cast<const unsigned char*>(buf);
 		const int total_size = size;
 
+		// gzip is defined in https://tools.ietf.org/html/rfc1952
+
 		// The zip header cannot be shorter than 10 bytes
 		if (size < 10 || buf == 0) return -1;
 
@@ -129,9 +131,14 @@ namespace libtorrent
 		int flags = buffer[3];
 
 		// check for reserved flag and make sure it's compressed with the correct metod
+		// we only support deflate
 		if (method != 8 || (flags & FRESERVED) != 0) return -1;
 
-		// skip time, xflags, OS code
+		// skip time, xflags, OS code. The first 10 bytes of the header:
+		// +---+---+---+---+---+---+---+---+---+---+
+		// |ID1|ID2|CM |FLG|     MTIME     |XFL|OS | (more-->)
+		// +---+---+---+---+---+---+---+---+---+---+
+
 		size -= 10;
 		buffer += 10;