diff --git a/src/sip/dialog.c b/src/sip/dialog.c
index 4585e22b6..f1cb6cadf 100644
--- a/src/sip/dialog.c
+++ b/src/sip/dialog.c
@@ -35,6 +35,7 @@ struct sip_dialog {
 	uint32_t lseq;
 	uint32_t rseq;
 	size_t cpos;
+	size_t rpos;
 	enum sip_transp tp;
 	uint32_t srcport;
 };
@@ -118,6 +119,7 @@ int sip_dialog_alloc(struct sip_dialog **dlgp,
 		if (i == 0)
 			rend = dlg->mb->pos - 2;
 	}
+	dlg->rpos = dlg->mb->pos;
 	err |= mbuf_printf(dlg->mb, "To: <%s>\r\n", to_uri);
 	dlg->cpos = dlg->mb->pos;
 	err |= mbuf_printf(dlg->mb, "From: %s%s%s<%s>;tag=%016llx\r\n",
@@ -231,7 +233,9 @@ int sip_dialog_accept(struct sip_dialog **dlgp, const struct sip_msg *msg)
 
 	err |= sip_msg_hdr_apply(msg, true, SIP_HDR_RECORD_ROUTE,
 				 record_route_handler, &renc) ? ENOMEM : 0;
+	dlg->rpos = dlg->mb->pos;
 	err |= mbuf_printf(dlg->mb, "To: %r\r\n", &msg->from.val);
+	dlg->cpos = dlg->mb->pos;
 	err |= mbuf_printf(dlg->mb, "From: %r;tag=%016llx\r\n", &msg->to.val,
 			   msg->tag);
 	if (err)
@@ -304,10 +308,12 @@ int sip_dialog_create(struct sip_dialog *dlg, const struct sip_msg *msg)
 
 	err |= sip_msg_hdr_apply(msg, msg->req, SIP_HDR_RECORD_ROUTE,
 				 record_route_handler, &renc) ? ENOMEM : 0;
+	dlg->rpos = renc.mb->pos;
 	err |= mbuf_printf(renc.mb, "To: %r\r\n",
 			   msg->req ? &msg->from.val : &msg->to.val);
 
 	dlg->mb->pos = dlg->cpos;
+	dlg->cpos = renc.mb->pos;
 	err |= mbuf_write_mem(renc.mb, mbuf_buf(dlg->mb),
 			      mbuf_get_left(dlg->mb));
 	dlg->mb->pos = 0;
@@ -344,7 +350,6 @@ int sip_dialog_create(struct sip_dialog *dlg, const struct sip_msg *msg)
 	dlg->rtag = mem_ref(rtag);
 	dlg->uri  = mem_ref(uri);
 	dlg->rseq = msg->req ? msg->cseq.num : 0;
-	dlg->cpos = 0;
 	dlg->tp   = msg->tp;
 
  out:
@@ -462,6 +467,8 @@ int sip_dialog_update(struct sip_dialog *dlg, const struct sip_msg *msg)
 {
 	const struct sip_hdr *contact;
 	struct sip_addr addr;
+	struct mbuf *mb;
+	size_t cpos;
 	char *uri;
 	int err;
 
@@ -479,6 +486,28 @@ int sip_dialog_update(struct sip_dialog *dlg, const struct sip_msg *msg)
 	if (err)
 		return err;
 
+	mb = mbuf_alloc(512);
+	if (!mb)
+		return ENOMEM;
+
+	err = mbuf_write_mem(mb, mbuf_buf(dlg->mb), dlg->rpos);
+	err |= mbuf_printf(mb, "To: %r\r\n",
+		   msg->req ? &msg->from.val : &msg->to.val);
+	cpos = mb->pos;
+	err |= mbuf_write_mem(mb, mbuf_buf(dlg->mb) + dlg->cpos,
+			      mbuf_get_left(dlg->mb) - dlg->cpos);
+
+	if (err)
+		goto out;
+
+	dlg->cpos = cpos;
+	mb->pos = 0;
+
+	mem_deref(dlg->rtag);
+	err = pl_strdup(&dlg->rtag, msg->req ? &msg->from.tag : &msg->to.tag);
+	if (err)
+		return err;
+
 	if (dlg->route.scheme.p == dlg->uri) {
 
 		struct uri tmp;
@@ -492,10 +521,14 @@ int sip_dialog_update(struct sip_dialog *dlg, const struct sip_msg *msg)
 		dlg->route = tmp;
 	}
 
+	mem_deref(dlg->mb);
 	mem_deref(dlg->uri);
+
+	dlg->mb = mem_ref(mb);
 	dlg->uri = mem_ref(uri);
 
  out:
+	mem_deref(mb);
 	mem_deref(uri);
 
 	return err;