Index: win_iocp_socket_service_base.ipp
===================================================================
--- win_iocp_socket_service_base.ipp	(revision 85729)
+++ win_iocp_socket_service_base.ipp	(working copy)
@@ -351,14 +351,13 @@
     iocp_service_.on_completion(op, boost::asio::error::bad_descriptor);
   else
   {
-    DWORD bytes_transferred = 0;
     int result = ::WSASend(impl.socket_, buffers,
-        static_cast<DWORD>(buffer_count), &bytes_transferred, flags, op, 0);
+        static_cast<DWORD>(buffer_count), NULL, flags, op, 0);
     DWORD last_error = ::WSAGetLastError();
     if (last_error == ERROR_PORT_UNREACHABLE)
       last_error = WSAECONNREFUSED;
     if (result != 0 && last_error != WSA_IO_PENDING)
-      iocp_service_.on_completion(op, last_error, bytes_transferred);
+      iocp_service_.on_completion(op, last_error, 0);
     else
       iocp_service_.on_pending(op);
   }
@@ -377,15 +376,14 @@
     iocp_service_.on_completion(op, boost::asio::error::bad_descriptor);
   else
   {
-    DWORD bytes_transferred = 0;
     int result = ::WSASendTo(impl.socket_, buffers,
         static_cast<DWORD>(buffer_count),
-        &bytes_transferred, flags, addr, addrlen, op, 0);
+        NULL, flags, addr, addrlen, op, 0);
     DWORD last_error = ::WSAGetLastError();
     if (last_error == ERROR_PORT_UNREACHABLE)
       last_error = WSAECONNREFUSED;
     if (result != 0 && last_error != WSA_IO_PENDING)
-      iocp_service_.on_completion(op, last_error, bytes_transferred);
+      iocp_service_.on_completion(op, last_error, 0);
     else
       iocp_service_.on_pending(op);
   }
@@ -405,18 +403,17 @@
     iocp_service_.on_completion(op, boost::asio::error::bad_descriptor);
   else
   {
-    DWORD bytes_transferred = 0;
     DWORD recv_flags = flags;
     int result = ::WSARecv(impl.socket_, buffers,
         static_cast<DWORD>(buffer_count),
-        &bytes_transferred, &recv_flags, op, 0);
+        NULL, &recv_flags, op, 0);
     DWORD last_error = ::WSAGetLastError();
     if (last_error == ERROR_NETNAME_DELETED)
       last_error = WSAECONNRESET;
     else if (last_error == ERROR_PORT_UNREACHABLE)
       last_error = WSAECONNREFUSED;
     if (result != 0 && last_error != WSA_IO_PENDING)
-      iocp_service_.on_completion(op, last_error, bytes_transferred);
+      iocp_service_.on_completion(op, last_error, 0);
     else
       iocp_service_.on_pending(op);
   }
@@ -454,16 +451,15 @@
     iocp_service_.on_completion(op, boost::asio::error::bad_descriptor);
   else
   {
-    DWORD bytes_transferred = 0;
     DWORD recv_flags = flags;
     int result = ::WSARecvFrom(impl.socket_, buffers,
         static_cast<DWORD>(buffer_count),
-        &bytes_transferred, &recv_flags, addr, addrlen, op, 0);
+        NULL, &recv_flags, addr, addrlen, op, 0);
     DWORD last_error = ::WSAGetLastError();
     if (last_error == ERROR_PORT_UNREACHABLE)
       last_error = WSAECONNREFUSED;
     if (result != 0 && last_error != WSA_IO_PENDING)
-      iocp_service_.on_completion(op, last_error, bytes_transferred);
+      iocp_service_.on_completion(op, last_error, 0);
     else
       iocp_service_.on_pending(op);
   }