--- a/plugins/mod_muc_mam.lua	Thu Oct 25 15:33:46 2018 +0100
+++ b/plugins/mod_muc_mam.lua	Thu Oct 25 21:21:22 2018 +0200
@@ -98,7 +98,7 @@
 -- Serve form
 module:hook("iq-get/bare/"..xmlns_mam..":query", function(event)
 	local origin, stanza = event.origin, event.stanza;
-	origin.send(st.reply(stanza):add_child(query_form:form()));
+	origin.send(st.reply(stanza):tag("query", { xmlns = xmlns_mam }):add_child(query_form:form()));
 	return true;
 end);