--- a/util/xml.lua	Sat Oct 03 15:09:12 2020 +0200
+++ b/util/xml.lua	Sat Oct 03 16:22:56 2020 +0200
@@ -71,7 +71,7 @@
 		if ok then
 			return stanza.tags[1];
 		else
-			return ok, err.." (line "..line..", col "..col..")";
+			return ok, ("%s (line %d, col %d))"):format(err, line, col);
 		end
 	end;
 end)();