--- a/plugins/mod_mam/mod_mam.lua	Thu Jul 11 23:26:02 2019 +0200
+++ b/plugins/mod_mam/mod_mam.lua	Thu Jul 11 23:31:13 2019 +0200
@@ -197,7 +197,7 @@
 	end
 
 	-- That's all folks!
-	module:log("debug", "Archive query %s completed", tostring(qid));
+	module:log("debug", "Archive query id=%s completed", qid or stanza.attr.id);
 
 	origin.send(st.reply(stanza)
 		:tag("fin", { xmlns = xmlns_mam, queryid = qid, complete = complete })