diff --git a/xep-0177.xml b/xep-0177.xml
index 95ebbdac..de587fe1 100644
--- a/xep-0177.xml
+++ b/xep-0177.xml
@@ -409,6 +409,7 @@ INITIATOR                            RESPONDER
   <xs:complexType name='candidateElementType'>
     <xs:simpleContent>
       <xs:extension base='empty'>
+        <xs:attribute name='component' type='xs:unsignedByte' use='required'/>
         <xs:attribute name='generation' type='xs:unsignedByte' use='required'/>
         <xs:attribute name='id' type='xs:NCName' use='required'/>
         <xs:attribute name='ip' type='xs:string' use='required'/>