diff --git a/xep.ent b/xep.ent
index f7cf4449..82199946 100644
--- a/xep.ent
+++ b/xep.ent
@@ -595,6 +595,7 @@ THE SOFTWARE.
 <!ENTITY rfc5450 "<span class='ref'><link url='http://tools.ietf.org/html/rfc5450'>RFC 5450</link></span> <note>RFC 5450: Transmission Time Offsets in RTP Streams &lt;<link url='http://tools.ietf.org/html/rfc5450'>http://tools.ietf.org/html/rfc5450</link>&gt;.</note>" >
 <!ENTITY rfc5547 "<span class='ref'><link url='http://tools.ietf.org/html/rfc5547'>RFC 5547</link></span> <note>RFC 5547: A Session Description Protocol (SDP) Offer/Answer Mechanism to Enable File Transfer &lt;<link url='http://tools.ietf.org/html/rfc5547'>http://tools.ietf.org/html/rfc5547</link>&gt;.</note>" >
 <!ENTITY rfc5574 "<span class='ref'><link url='http://tools.ietf.org/html/rfc5574'>RFC 5574</link></span> <note>RFC 5574: RTP Payload Format for the Speex Codec &lt;<link url='http://tools.ietf.org/html/rfc5574'>http://tools.ietf.org/html/rfc5574</link>&gt;.</note>" >
+<!ENTITY rfc5646 "<span class='ref'><link url='http://tools.ietf.org/html/rfc5646'>RFC 5646</link></span> <note>RFC 5646: Tags for Identifying Languages &lt;<link url='http://tools.ietf.org/html/rfc5646'>http://tools.ietf.org/html/rfc5646</link>&gt;.</note>" >
 <!ENTITY rfc5802 "<span class='ref'><link url='http://tools.ietf.org/html/rfc5802'>RFC 5802</link></span> <note>RFC 5802: Salted Challenge Response Authentication Mechanism (SCRAM) SASL and GSS-API Mechanisms &lt;<link url='http://tools.ietf.org/html/rfc5802'>http://tools.ietf.org/html/rfc5802</link>&gt;.</note>" >
 <!ENTITY rfc5952 "<span class='ref'><link url='http://tools.ietf.org/html/rfc5952'>RFC 5952</link></span> <note>RFC 5952: A Recommendation for IPv6 Address Text Representation &lt;<link url='http://tools.ietf.org/html/rfc5952'>http://tools.ietf.org/html/rfc5952</link>&gt;.</note>" >
 <!ENTITY rfc6051 "<span class='ref'><link url='http://tools.ietf.org/html/rfc6051'>RFC 6051</link></span> <note>RFC 6051: Rapid Synchronisation of RTP Flows &lt;<link url='http://tools.ietf.org/html/rfc6051'>http://tools.ietf.org/html/rfc6051</link>&gt;.</note>" >