demux.proc = sideband_demux;
                demux.data = fd;
                demux.out = -1;
+               demux.isolate_sigpipe = 1;
                if (start_async(&demux))
                        die("send-pack: unable to fork off sideband demultiplexer");
                in = demux.out;
                                close(out);
                        if (git_connection_is_socket(conn))
                                shutdown(fd[0], SHUT_WR);
-                       if (use_sideband)
+                       if (use_sideband) {
+                               close(demux.out);
                                finish_async(&demux);
+                       }
                        fd[1] = -1;
                        return -1;
                }
                packet_flush(out);
 
        if (use_sideband && cmds_sent) {
+               close(demux.out);
                if (finish_async(&demux)) {
                        error("error in sideband demultiplexer");
                        ret = -1;
                }
-               close(demux.out);
        }
 
        if (ret < 0)