diff --git a/model/sync-seq-no.h b/model/sync-seq-no.h
index ae7f355..93013a5 100644
--- a/model/sync-seq-no.h
+++ b/model/sync-seq-no.h
@@ -142,7 +142,7 @@
 inline std::ostream &
 operator << (std::ostream &os, const SeqNo &seqno)
 {
-  os << seqno.getSession () << ":" << seqno.getSeq ();
+  os << "<session>" << seqno.getSession () << "</session><seqno>" << seqno.getSeq () << "</seqno>";
   return os;
 }