diff --git a/src/irclib.py b/src/irclib.py
index 3ffb1de1c..f994d4de9 100644
--- a/src/irclib.py
+++ b/src/irclib.py
@@ -624,9 +624,14 @@ class IrcState(IrcCommandDispatcher, log.Firewalled):
         Supported user and channel modes are cached"""
         # msg.args = [nick, server, ircd-version, umodes, modes,
         #             modes that require arguments? (non-standard)]
-        self.ircd = msg.args[2] if len(msg.args) >= 3 else msg.args[1]
-        self.supported['umodes'] = frozenset(msg.args[3])
-        self.supported['chanmodes'] = frozenset(msg.args[4])
+        self.ircd = msg.args[2] if len(msg.args) > 2 else msg.args[1]
+
+        # The conditionals are for Twitch, which doesn't send umodes or
+        # chanmodes.
+        if len(msg.args) > 3:
+            self.supported['umodes'] = frozenset(msg.args[3])
+        if len(msg.args) > 4:
+            self.supported['chanmodes'] = frozenset(msg.args[4])
 
     _005converters = utils.InsensitivePreservingDict({
         'modes': lambda s: int(s) if s else None,  # it's optional
diff --git a/test/test_irclib.py b/test/test_irclib.py
index da216c210..a3c328e5e 100644
--- a/test/test_irclib.py
+++ b/test/test_irclib.py
@@ -387,6 +387,12 @@ class IrcStateTestCase(SupyTestCase):
         self.assertEqual(state.supported['chanmodes'],
                          frozenset('biklmnopstveI'))
 
+    def testShort004(self):
+        state = irclib.IrcState()
+        state.addMsg(self.irc, ircmsgs.IrcMsg(':coulomb.oftc.net 004 testnick coulomb.oftc.net hybrid-7.2.2+oftc1.6.8'))
+        self.assertNotIn('umodes', state.supported)
+        self.assertNotIn('chanmodes', state.supported)
+
     def testEmptyTopic(self):
         state = irclib.IrcState()
         state.addMsg(self.irc, ircmsgs.topic('#foo'))