--- a/plugins/muc/subject.lib.lua	Fri Jun 01 08:02:43 2018 +0200
+++ b/plugins/muc/subject.lib.lua	Fri Jun 01 08:03:12 2018 +0200
@@ -73,6 +73,13 @@
 	return true;
 end
 
+module:hook("muc-disco#info", function (event)
+	table.insert(event.form, {
+		name = "muc#roominfo_subject";
+	});
+	event.formdata["muc#roominfo_subject"] = select(2, get_subject(event.room));
+end);
+
 -- Send subject to joining user
 module:hook("muc-occupant-session-new", function(event)
 	send_subject(event.room, event.stanza.attr.from);