Index: channels/chan_mgcp.c
===================================================================
--- channels/chan_mgcp.c	(revision 280877)
+++ channels/chan_mgcp.c	(working copy)
@@ -3580,7 +3580,7 @@
 	if (sscanf(req->identifier, "%30d", &seqno) != 1) {
 		seqno = 0;
 	}
-	for (cur = sub->parent->parent->responses, next = cur->next; cur; cur = next, next = cur->next) {
+	for (cur = sub->parent->parent->responses, next = cur ? cur->next : NULL; cur; cur = next, next = cur ? cur->next : NULL) {
 		if (now - cur->whensent > RESPONSE_TIMEOUT) {
 			/* Delete this entry */
 			if (prev)