--- channels.orig/chan_sip.c	2012-07-11 19:43:13.000000000 +0200
+++ channels/chan_sip.c	2012-07-11 19:45:27.000000000 +0200
@@ -5767,7 +5767,7 @@
 	}
 
 	/* Remove link from peer to subscription of MWI */
-	if (p->relatedpeer && p->relatedpeer->mwipvt)
+	if (p->relatedpeer && p->relatedpeer->mwipvt == p)
 		p->relatedpeer->mwipvt = dialog_unref(p->relatedpeer->mwipvt, "delete ->relatedpeer->mwipvt");
 	if (p->relatedpeer && p->relatedpeer->call == p)
 		p->relatedpeer->call = dialog_unref(p->relatedpeer->call, "unset the relatedpeer->call field in tandem with relatedpeer field itself");