--- a/plugins/muc/muc.lib.lua	Mon Aug 19 12:17:17 2019 +0100
+++ b/plugins/muc/muc.lib.lua	Wed Aug 21 00:36:42 2019 +0200
@@ -359,6 +359,7 @@
 module:hook("muc-disco#info", function(event)
 	event.reply:tag("feature", {var = "http://jabber.org/protocol/muc"}):up();
 	event.reply:tag("feature", {var = "http://jabber.org/protocol/muc#stable_id"}):up();
+	event.reply:tag("feature", {var = "http://jabber.org/protocol/muc#self-ping-optimization"}):up();
 end);
 module:hook("muc-disco#info", function(event)
 	table.insert(event.form, { name = "muc#roominfo_occupants", label = "Number of occupants" });