diff --git a/include/libtorrent/udp_socket.hpp b/include/libtorrent/udp_socket.hpp
index 79b301b49..f26726ed6 100644
--- a/include/libtorrent/udp_socket.hpp
+++ b/include/libtorrent/udp_socket.hpp
@@ -64,6 +64,10 @@ namespace libtorrent
 		void set_proxy_settings(proxy_settings const& ps);
 		proxy_settings const& get_proxy_settings() { return m_proxy_settings; }
 
+#ifndef NDEBUG
+		~udp_socket() { m_magic = 0; }
+#endif
+
 	private:
 
 		callback_t m_callback;
@@ -94,6 +98,7 @@ namespace libtorrent
 		char m_v4_buf[1600];
 		char m_v6_buf[1600];
 		int m_bind_port;
+		uint8_t m_outstanding;
 
 		tcp::socket m_socks5_sock;
 		int m_connection_ticket;
@@ -103,6 +108,9 @@ namespace libtorrent
 		char m_tmp_buf[100];
 		bool m_tunnel_packets;
 		udp::endpoint m_proxy_addr;
+#ifndef NDEBUG
+		int m_magic;
+#endif
 	};
 }
 
diff --git a/src/udp_socket.cpp b/src/udp_socket.cpp
index 3a5c00892..8f0aefb9f 100644
--- a/src/udp_socket.cpp
+++ b/src/udp_socket.cpp
@@ -18,20 +18,33 @@ udp_socket::udp_socket(asio::io_service& ios, udp_socket::callback_t const& c
 	, m_ipv4_sock(ios)
 	, m_ipv6_sock(ios)
 	, m_bind_port(0)
+	, m_outstanding(0)
 	, m_socks5_sock(ios)
 	, m_connection_ticket(-1)
 	, m_cc(cc)
 	, m_resolver(ios)
 	, m_tunnel_packets(false)
 {
+#ifndef NDEBUG
+	m_magic = 0x1337;
+#endif
 }
 
+#ifndef NDEBUG
+	#define CHECK_MAGIC check_magic_ cm_(m_magic)
+	struct check_magic_
+	{
+		check_magic_(int& m_): m(m_) { TORRENT_ASSERT(m == 0x1337); }
+		~check_magic_() { TORRENT_ASSERT(m == 0x1337); }
+		int& m;
+	};
+#else
+	#define CHECK_MAGIC (void)
+#endif
+
 void udp_socket::send(udp::endpoint const& ep, char const* p, int len, error_code& ec)
 {
-	if (ec == asio::error::operation_aborted) return;
-
-	mutex_t::scoped_lock l(m_mutex);	
-
+	CHECK_MAGIC;
 	if (m_tunnel_packets)
 	{
 		// send udp packets through SOCKS5 server
@@ -47,10 +60,26 @@ void udp_socket::send(udp::endpoint const& ep, char const* p, int len, error_cod
 
 void udp_socket::on_read(udp::socket* s, error_code const& e, std::size_t bytes_transferred)
 {
-	if (e == asio::error::operation_aborted) return;
-
+	TORRENT_ASSERT(m_magic == 0x1337);
 	mutex_t::scoped_lock l(m_mutex);	
 
+	TORRENT_ASSERT(m_outstanding > 0);
+	--m_outstanding;
+
+	if (e == asio::error::operation_aborted)
+	{
+		if (m_outstanding == 0)
+		{
+			// "this" may be destructed in the callback
+			// that's why we need to unlock
+			l.unlock();
+			callback_t tmp = m_callback;
+			m_callback.clear();
+		}
+		return;
+	}
+
+	CHECK_MAGIC;
 	if (!m_callback) return;
 
 	if (e)
@@ -59,9 +88,9 @@ void udp_socket::on_read(udp::socket* s, error_code const& e, std::size_t bytes_
 		try {
 #endif
 		if (s == &m_ipv4_sock)
-			get_io_service().post(boost::bind(m_callback, e, m_v4_ep, (char*)0, 0));
+			m_callback(e, m_v4_ep, 0, 0);
 		else
-			get_io_service().post(boost::bind(m_callback, e, m_v6_ep, (char*)0, 0));
+			m_callback(e, m_v6_ep, 0, 0);
 #ifndef BOOST_NO_EXCEPTIONS
 		} catch(std::exception&) {}
 #endif
@@ -94,7 +123,7 @@ void udp_socket::on_read(udp::socket* s, error_code const& e, std::size_t bytes_
 		if (m_tunnel_packets && m_v4_ep == m_proxy_addr)
 			unwrap(e, m_v4_buf, bytes_transferred);
 		else
-			get_io_service().post(boost::bind(m_callback, e, m_v4_ep, m_v4_buf, bytes_transferred));
+			m_callback(e, m_v4_ep, m_v4_buf, bytes_transferred);
 
 #ifndef BOOST_NO_EXCEPTIONS
 		} catch(std::exception&) {}
@@ -111,7 +140,7 @@ void udp_socket::on_read(udp::socket* s, error_code const& e, std::size_t bytes_
 		if (m_tunnel_packets && m_v6_ep == m_proxy_addr)
 			unwrap(e, m_v6_buf, bytes_transferred);
 		else
-			get_io_service().post(boost::bind(m_callback, e, m_v6_ep, m_v6_buf, bytes_transferred));
+			m_callback(e, m_v6_ep, m_v6_buf, bytes_transferred);
 
 #ifndef BOOST_NO_EXCEPTIONS
 		} catch(std::exception&) {}
@@ -119,10 +148,12 @@ void udp_socket::on_read(udp::socket* s, error_code const& e, std::size_t bytes_
 		s->async_receive_from(asio::buffer(m_v6_buf, sizeof(m_v6_buf))
 			, m_v6_ep, boost::bind(&udp_socket::on_read, this, s, _1, _2));
 	}
+	++m_outstanding;
 }
 
 void udp_socket::wrap(udp::endpoint const& ep, char const* p, int len, error_code& ec)
 {
+	CHECK_MAGIC;
 	using namespace libtorrent::detail;
 
 	char header[20];
@@ -147,6 +178,7 @@ void udp_socket::wrap(udp::endpoint const& ep, char const* p, int len, error_cod
 // unwrap the UDP packet from the SOCKS5 header
 void udp_socket::unwrap(error_code const& e, char const* buf, int size)
 {
+	CHECK_MAGIC;
 	using namespace libtorrent::detail;
 
 	// the minimum socks5 header size
@@ -177,27 +209,37 @@ void udp_socket::unwrap(error_code const& e, char const* buf, int size)
 		return;
 	}
 
-	get_io_service().post(boost::bind(m_callback, e, sender, p, size - (p - buf)));
+	m_callback(e, sender, p, size - (p - buf));
 }
 
 void udp_socket::close()
 {
+	TORRENT_ASSERT(m_magic == 0x1337);
 	mutex_t::scoped_lock l(m_mutex);	
 
 	error_code ec;
 	m_ipv4_sock.close(ec);
 	m_ipv6_sock.close(ec);
 	m_socks5_sock.close(ec);
-	m_callback.clear();
 	if (m_connection_ticket >= 0)
 	{
 		m_cc.done(m_connection_ticket);
 		m_connection_ticket = -1;
 	}
+
+	if (m_outstanding == 0)
+	{
+		// "this" may be destructed in the callback
+		// that's why we need to unlock
+		l.unlock();
+		callback_t tmp = m_callback;
+		m_callback.clear();
+	}
 }
 
 void udp_socket::bind(udp::endpoint const& ep, error_code& ec)
 {
+	CHECK_MAGIC;
 	mutex_t::scoped_lock l(m_mutex);	
 
 	if (m_ipv4_sock.is_open()) m_ipv4_sock.close(ec);
@@ -221,11 +263,13 @@ void udp_socket::bind(udp::endpoint const& ep, error_code& ec)
 		m_ipv6_sock.async_receive_from(asio::buffer(m_v6_buf, sizeof(m_v6_buf))
 			, m_v6_ep, boost::bind(&udp_socket::on_read, this, &m_ipv6_sock, _1, _2));
 	}
+	++m_outstanding;
 	m_bind_port = ep.port();
 }
 
 void udp_socket::bind(int port)
 {
+	CHECK_MAGIC;
 	mutex_t::scoped_lock l(m_mutex);	
 
 	error_code ec;
@@ -239,6 +283,7 @@ void udp_socket::bind(int port)
 		m_ipv4_sock.bind(udp::endpoint(address_v4::any(), port), ec);
 		m_ipv4_sock.async_receive_from(asio::buffer(m_v4_buf, sizeof(m_v4_buf))
 			, m_v4_ep, boost::bind(&udp_socket::on_read, this, &m_ipv4_sock, _1, _2));
+		++m_outstanding;
 	}
 	m_ipv6_sock.open(udp::v6(), ec);
 	if (!ec)
@@ -247,12 +292,14 @@ void udp_socket::bind(int port)
 		m_ipv6_sock.bind(udp::endpoint(address_v6::any(), port), ec);
 		m_ipv6_sock.async_receive_from(asio::buffer(m_v6_buf, sizeof(m_v6_buf))
 			, m_v6_ep, boost::bind(&udp_socket::on_read, this, &m_ipv6_sock, _1, _2));
+		++m_outstanding;
 	}
 	m_bind_port = port;
 }
 
 void udp_socket::set_proxy_settings(proxy_settings const& ps)
 {
+	CHECK_MAGIC;
 	mutex_t::scoped_lock l(m_mutex);	
 
 	error_code ec;
@@ -275,6 +322,7 @@ void udp_socket::set_proxy_settings(proxy_settings const& ps)
 void udp_socket::on_name_lookup(error_code const& e, tcp::resolver::iterator i)
 {
 	if (e) return;
+	CHECK_MAGIC;
 
 	mutex_t::scoped_lock l(m_mutex);	
 
@@ -286,6 +334,7 @@ void udp_socket::on_name_lookup(error_code const& e, tcp::resolver::iterator i)
 
 void udp_socket::on_timeout()
 {
+	CHECK_MAGIC;
 	mutex_t::scoped_lock l(m_mutex);	
 
 	error_code ec;
@@ -295,6 +344,7 @@ void udp_socket::on_timeout()
 
 void udp_socket::on_connect(int ticket)
 {
+	CHECK_MAGIC;
 	mutex_t::scoped_lock l(m_mutex);	
 
 	m_connection_ticket = ticket;
@@ -306,12 +356,13 @@ void udp_socket::on_connect(int ticket)
 
 void udp_socket::on_connected(error_code const& e)
 {
+	CHECK_MAGIC;
+
+	mutex_t::scoped_lock l(m_mutex);	
 	m_cc.done(m_connection_ticket);
 	m_connection_ticket = -1;
 	if (e) return;
 
-	mutex_t::scoped_lock l(m_mutex);	
-
 	using namespace libtorrent::detail;
 
 	// send SOCKS5 authentication methods
@@ -335,6 +386,7 @@ void udp_socket::on_connected(error_code const& e)
 
 void udp_socket::handshake1(error_code const& e)
 {
+	CHECK_MAGIC;
 	if (e) return;
 
 	mutex_t::scoped_lock l(m_mutex);	
@@ -345,6 +397,7 @@ void udp_socket::handshake1(error_code const& e)
 
 void udp_socket::handshake2(error_code const& e)
 {
+	CHECK_MAGIC;
 	if (e) return;
 
 	using namespace libtorrent::detail;
@@ -390,6 +443,7 @@ void udp_socket::handshake2(error_code const& e)
 
 void udp_socket::handshake3(error_code const& e)
 {
+	CHECK_MAGIC;
 	if (e) return;
 
 	mutex_t::scoped_lock l(m_mutex);	
@@ -400,6 +454,7 @@ void udp_socket::handshake3(error_code const& e)
 
 void udp_socket::handshake4(error_code const& e)
 {
+	CHECK_MAGIC;
 	if (e) return;
 
 	mutex_t::scoped_lock l(m_mutex);	
@@ -418,6 +473,7 @@ void udp_socket::handshake4(error_code const& e)
 
 void udp_socket::socks_forward_udp()
 {
+	CHECK_MAGIC;
 	using namespace libtorrent::detail;
 
 	mutex_t::scoped_lock l(m_mutex);	
@@ -437,6 +493,7 @@ void udp_socket::socks_forward_udp()
 
 void udp_socket::connect1(error_code const& e)
 {
+	CHECK_MAGIC;
 	if (e) return;
 
 	mutex_t::scoped_lock l(m_mutex);	
@@ -447,6 +504,7 @@ void udp_socket::connect1(error_code const& e)
 
 void udp_socket::connect2(error_code const& e)
 {
+	CHECK_MAGIC;
 	if (e) return;
 
 	mutex_t::scoped_lock l(m_mutex);