diff -up openssh-5.6p1/clientloop.c.clientloop openssh-5.6p1/clientloop.c
--- openssh-5.6p1/clientloop.c.clientloop	2010-11-24 08:18:10.000000000 +0100
+++ openssh-5.6p1/clientloop.c	2010-11-24 08:18:11.000000000 +0100
@@ -1944,7 +1944,7 @@ client_input_channel_req(int type, u_int
 		}
 		packet_check_eom();
 	}
-	if (reply) {
+	if (reply && c != NULL) {
 		packet_start(success ?
 		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
 		packet_put_int(c->remote_id);