diff -r bad1be5e4674 -r 68dc84e72bef plugins/ping.lua
--- a/plugins/ping.lua	Sun May 27 17:30:37 2018 +0200
+++ b/plugins/ping.lua	Sun May 27 17:34:33 2018 +0200
@@ -6,6 +6,8 @@
 		local jid = command.param;
 		if jid then
 			jid = bot:resolvejid(jid, command.room);
+		end
+		if jid then
 			bot.stream:ping(jid, function (time, jid, error)
 				if time then
 					command:reply(string.format("Pong from %s in %0.3f seconds", jid, time));