diff --git a/commands/roster.py b/commands/roster.py
index 193ad33..67de602 100644
--- a/commands/roster.py
+++ b/commands/roster.py
@@ -4,6 +4,9 @@ unhighlight_nick = lambda nick: "_{!s}_".format(nick)
 
 @plugin.command("roster","<filter>")
 def on_roster(self,channel,nick,*namecnt):
+	if not namecnt:
+		self.say(channel,"{}: Must supply a filter!".format(nick))
+		return
 	output = subprocess.check_output(["/usr/local/bin/roster",' '.join(namecnt)]).decode("utf-8").split("\n")
 	output = filter(None,output)
 	for line in output: