diff --git a/include/osmocom/msc/gsm_04_80.h b/include/osmocom/msc/gsm_04_80.h
index 29b800b..073794b 100644
--- a/include/osmocom/msc/gsm_04_80.h
+++ b/include/osmocom/msc/gsm_04_80.h
@@ -10,4 +10,5 @@
 
 int msc_send_ussd_notify(struct ran_conn *conn, int level,
 			 const char *text);
-int msc_send_ussd_release_complete(struct ran_conn *conn);
+int msc_send_ussd_release_complete(struct ran_conn *conn,
+				   uint8_t transaction_id);