diff --git a/plugins/Later/plugin.py b/plugins/Later/plugin.py
index b382559af..6c423b4e6 100644
--- a/plugins/Later/plugin.py
+++ b/plugins/Later/plugin.py
@@ -41,7 +41,6 @@ import supybot.callbacks as callbacks
 from supybot.i18n import PluginInternationalization, internationalizeDocstring
 _ = PluginInternationalization('Later')
 
-
 class Later(callbacks.Plugin):
     """Used to do things later; currently, it only allows the sending of
     nick-based notes.  Do note (haha!) that these notes are *not* private
@@ -102,6 +101,25 @@ class Later(callbacks.Plugin):
             self.wildcards.append(nick)
         self._flushNotes()
 
+    def _validateNick(self, nick):
+        """Validate nick according to the IRC RFC 2812 spec.
+
+        Reference: http://tools.ietf.org/rfcmarkup?doc=2812#section-2.3.1
+
+        Some irc clients' tab-completion feature appends 'address' characters
+        to nick, such as ':' or ','. We try correcting for that by trimming
+        a char off the end.
+
+        If nick incorrigibly invalid, return False, otherwise,
+        return (possibly trimmed) nick.
+        """
+        if not ircutils.isNick(nick, strictRfc=True):
+            if not ircutils.isNick(nick[:-1], strictRfc=True):
+                return False
+            else:
+                return nick[:-1]
+        return nick
+
     @internationalizeDocstring
     def tell(self, irc, msg, args, nick, text):
         """<nick> <text>
@@ -113,8 +131,12 @@ class Later(callbacks.Plugin):
         if ircutils.strEqual(nick, irc.nick):
             irc.error(_('I can\'t send notes to myself.'))
             return
+        validnick = self._validateNick(nick)
+        if validnick is False:
+            irc.error('That is an invalid IRC nick. Please check your input.')
+            return
         try:
-            self._addNote(nick, msg.nick, text)
+            self._addNote(validnick, msg.nick, text)
             irc.replySuccess()
         except ValueError:
             irc.error(_('That person\'s message queue is already full.'))
diff --git a/plugins/Later/test.py b/plugins/Later/test.py
index dc3a95069..d91070620 100644
--- a/plugins/Later/test.py
+++ b/plugins/Later/test.py
@@ -43,6 +43,11 @@ class LaterTestCase(PluginTestCase):
         self.assertNotRegexp('later notes', 'bar.*foo')
         self.assertRegexp('later notes', 'foo')
 
+    def testNickValidation(self):
+        self.assertError('later tell 1foo bar')
+        self.assertError('later tell foo$moo zoob')
+        self.assertNotError('later tell foo: baz')
+        self.assertRegexp('later notes', 'foo\.')
 
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