diff --git a/openbsc/src/libbsc/bsc_msc.c b/openbsc/src/libbsc/bsc_msc.c
index a24efab..fc4530c 100644
--- a/openbsc/src/libbsc/bsc_msc.c
+++ b/openbsc/src/libbsc/bsc_msc.c
@@ -276,7 +276,7 @@
 	osmo_timer_schedule(&con->reconnect_timer, 5, 0);
 }
 
-struct msgb *bsc_msc_id_get_resp(const char *token)
+struct msgb *bsc_msc_id_get_resp(int fixed, const char *token)
 {
 	struct msgb *msg;
 
@@ -291,8 +291,21 @@
 		return NULL;
 	}
 
+	/*
+	 * The situation is bizarre. The encoding doesn't follow the
+	 * TLV structure. It is more like a LV and old versions had
+	 * it wrong but we want new versions to old servers so we
+	 * introduce the quirk here.
+	 */
 	msg->l2h = msgb_v_put(msg, IPAC_MSGT_ID_RESP);
-	msgb_l16tv_put(msg, strlen(token) + 1,
+	if (fixed) {
+		msgb_put_u8(msg, 0);
+		msgb_put_u8(msg, strlen(token) + 2);
+		msgb_tv_fixed_put(msg, IPAC_IDTAG_UNITNAME, strlen(token) + 1, (uint8_t *) token);
+	} else {
+		msgb_l16tv_put(msg, strlen(token) + 1,
 			IPAC_IDTAG_UNITNAME, (uint8_t *) token);
+	}
+
 	return msg;
 }
diff --git a/openbsc/src/osmo-bsc/osmo_bsc_msc.c b/openbsc/src/osmo-bsc/osmo_bsc_msc.c
index 129b23e..5127ca8 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_msc.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_msc.c
@@ -456,7 +456,7 @@
 	struct msc_signal_data sig;
 	struct msgb *msg;
 
-	msg = bsc_msc_id_get_resp(data->bsc_token);
+	msg = bsc_msc_id_get_resp(0, data->bsc_token);
 	if (!msg)
 		return;
 	msc_queue_write(data->msc_con, msg, IPAC_PROTO_IPACCESS);
diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index 9216654..841262c 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_nat.c
@@ -357,7 +357,7 @@
 
 static void send_id_get_response(struct bsc_msc_connection *msc_con)
 {
-	struct msgb *msg = bsc_msc_id_get_resp(nat->token);
+	struct msgb *msg = bsc_msc_id_get_resp(0, nat->token);
 	if (!msg)
 		return;
 
@@ -960,7 +960,7 @@
 {
 	struct bsc_config *conf;
 	const char *token = (const char *) TLVP_VAL(tvp, IPAC_IDTAG_UNITNAME);
-	const int len = TLVP_LEN(tvp, IPAC_IDTAG_UNITNAME);
+	int len = TLVP_LEN(tvp, IPAC_IDTAG_UNITNAME);
 
 	if (bsc->cfg) {
 		LOGP(DNAT, LOGL_ERROR, "Reauth on fd %d bsc nr %d\n",
@@ -980,11 +980,18 @@
 		return;
 	}
 
+	/*
+	 * New systems have fixed the structure of the message but
+	 * we need to support old ones too.
+	 */
+	if (len >= 2 && token[len - 2] == '\0')
+		len -= 1;
+
 	conf = bsc_config_by_token(bsc->nat, token, len);
 	if (!conf) {
 		LOGP(DNAT, LOGL_ERROR,
-			"No bsc found for token '%s' on fd: %d.\n", token,
-			bsc->write_queue.bfd.fd);
+			"No bsc found for token '%s' len %d on fd: %d.\n", token,
+			bsc->write_queue.bfd.fd, len);
 		bsc_close_connection(bsc);
 		return;
 	}