diff --git a/xep.ent b/xep.ent
index f1260990..06b357fa 100644
--- a/xep.ent
+++ b/xep.ent
@@ -504,6 +504,7 @@ THE SOFTWARE.
RFC 4252 RFC 4252: The Secure Shell (SHS) Authentication Protocol <http://tools.ietf.org/html/rfc4252>." >
RFC 4253 RFC 4253: The Secure Shell (SSH) Transport Layer Protocol <http://tools.ietf.org/html/rfc4253>." >
RFC 4270 RFC 4270: Attacks on Cryptographic Hashes in Internet Protocols <http://tools.ietf.org/html/rfc4270>." >
+RFC 4281 RFC 4281: The Codecs Parameter for "Bucket" Media Types <http://tools.ietf.org/html/rfc4281>." >
RFC 4287 RFC 4287: The Atom Syndication Format <http://tools.ietf.org/html/rfc4287>." >
RFC 4301 RFC 4301: Security Architecture for the Internet Protocol <http://tools.ietf.org/html/rfc4301>." >
RFC 4306 RFC 4306: Internet Key Exchange (IKEv2) Protocol <http://tools.ietf.org/html/rfc4306>." >