--- a/mod_smacks/mod_smacks.lua	Wed Mar 06 17:46:57 2019 +0100
+++ b/mod_smacks/mod_smacks.lua	Wed Mar 06 21:25:47 2019 +0100
@@ -344,6 +344,7 @@
 	local h = tonumber(stanza.attr.h);
 	if not h then
 		origin:close{ condition = "invalid-xml"; text = "Missing or invalid 'h' attribute"; };
+		return;
 	end
 	local handled_stanza_count = h-origin.last_acknowledged_stanza;
 	local queue = origin.outgoing_stanza_queue;