diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index 3221e04998..cb15ca01bc 100644
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -19,6 +19,7 @@
 /*! \file
  *
  * \brief Implementation of Inter-Asterisk eXchange Version 2
+ *        as specified in RFC 5456
  *
  * \author Mark Spencer <markster@digium.com>
  *