--- a/plugins/muc/muc.lib.lua	Sun Feb 04 01:40:11 2018 +0100
+++ b/plugins/muc/muc.lib.lua	Thu Feb 15 02:54:52 2018 +0100
@@ -1378,7 +1378,7 @@
 			end
 		end
 		local history = self._history;
-		if history then
+		if history and history[1] ~= nil then
 			state._last_message = st.preserialize(history[#history].stanza);
 			state._last_message_at = history[#history].timestamp;
 		end