diff --git a/locales/de.po b/locales/de.po
index a2b751c57..42d84374d 100644
--- a/locales/de.po
+++ b/locales/de.po
@@ -955,8 +955,7 @@ msgstr ""
 #: ../src/conf.py:995
 msgid ""
 "Determines how many old messages the bot will\n"
-"    keep around in its history.  Changing this variable will not take effect\n"
-"    until the bot is restarted."
+"    keep around in its history."
 msgstr ""
 
 #: ../src/conf.py:1000
diff --git a/locales/fi.po b/locales/fi.po
index 0dfc9326a..d3673651e 100644
--- a/locales/fi.po
+++ b/locales/fi.po
@@ -1503,13 +1503,9 @@ msgstr ""
 #: src/conf.py:1019
 msgid ""
 "Determines how many old messages the bot will\n"
-"    keep around in its history.  Changing this variable will not take "
-"effect\n"
-"    until the bot is restarted."
+"    keep around in its history."
 msgstr ""
-"Määrittää kuinka vanhoja viestejä botti pitää historiassaan. Tämän "
-"asetusarvon\n"
-" muuttaminen ei vaikuta ennen uudelleenkäynnistystä."
+"Määrittää kuinka vanhoja viestejä botti pitää historiassaan."
 
 #: src/conf.py:1024
 #, fuzzy
diff --git a/locales/fr.po b/locales/fr.po
index 7980a7fa1..1638266a9 100644
--- a/locales/fr.po
+++ b/locales/fr.po
@@ -992,9 +992,8 @@ msgstr "Détermine quelle vhost le bot bindera    avant de se connecter au serve
 #: ../src/conf.py:1019
 msgid ""
 "Determines how many old messages the bot will\n"
-"    keep around in its history.  Changing this variable will not take effect\n"
-"    until the bot is restarted."
-msgstr "Détermine combien de vieux messages le bot    gardera dans son historique. Changer cette variable ne prend effet qu'après    avoir redémarré le bot."
+"    keep around in its history."
+msgstr "Détermine combien de vieux messages le bot    gardera dans son historique."
 
 #: ../src/conf.py:1024
 msgid ""
diff --git a/locales/it.po b/locales/it.po
index c4e5eb139..10bb7e147 100644
--- a/locales/it.po
+++ b/locales/it.po
@@ -1183,11 +1183,9 @@ msgstr ""
 #: src/conf.py:1019
 msgid ""
 "Determines how many old messages the bot will\n"
-"    keep around in its history.  Changing this variable will not take effect\n"
-"    until the bot is restarted."
+"    keep around in its history."
 msgstr ""
-"Determina quanti messaggi vecchi terrà il bot nella cronologia. La modifica\n"
-"    di questa variabile non avrà effetto finché non si riavvia il bot."
+"Determina quanti messaggi vecchi terrà il bot nella cronologia."
 
 #: src/conf.py:1024
 msgid ""
diff --git a/locales/messages.pot b/locales/messages.pot
index 54684508f..f07929209 100644
--- a/locales/messages.pot
+++ b/locales/messages.pot
@@ -982,8 +982,7 @@ msgstr ""
 #: src/conf.py:1019
 msgid ""
 "Determines how many old messages the bot will\n"
-"    keep around in its history.  Changing this variable will not take effect\n"
-"    until the bot is restarted."
+"    keep around in its history."
 msgstr ""
 
 #: src/conf.py:1024
diff --git a/src/conf.py b/src/conf.py
index 7069f5871..99c7e2e94 100644
--- a/src/conf.py
+++ b/src/conf.py
@@ -1038,8 +1038,7 @@ registerGlobalValue(supybot.protocols.irc, 'vhost',
 
 registerGlobalValue(supybot.protocols.irc, 'maxHistoryLength',
     registry.Integer(1000, _("""Determines how many old messages the bot will
-    keep around in its history.  Changing this variable will not take effect
-    until the bot is restarted.""")))
+    keep around in its history.""")))
 
 registerGlobalValue(supybot.protocols.irc, 'throttleTime',
     registry.Float(1.0, _("""A floating point number of seconds to throttle
diff --git a/src/irclib.py b/src/irclib.py
index 767ed552e..b46886c2d 100644
--- a/src/irclib.py
+++ b/src/irclib.py
@@ -346,6 +346,9 @@ class IrcState(IrcCommandDispatcher):
                  nicksToHostmasks=None, channels=None):
         if history is None:
             history = RingBuffer(conf.supybot.protocols.irc.maxHistoryLength())
+            def resize_history():
+                self.history.resize(conf.supybot.protocols.irc.maxHistoryLength())
+            conf.supybot.protocols.irc.maxHistoryLength.addCallback(resize_history)
         if supported is None:
             supported = utils.InsensitivePreservingDict()
         if nicksToHostmasks is None:
diff --git a/test/test_irclib.py b/test/test_irclib.py
index 8190ff5cd..038823496 100644
--- a/test/test_irclib.py
+++ b/test/test_irclib.py
@@ -36,10 +36,8 @@ import supybot.conf as conf
 import supybot.irclib as irclib
 import supybot.ircmsgs as ircmsgs
 
-# The test framework used to provide these, but not it doesn't.  We'll add
-# messages to as we find bugs (if indeed we find bugs).
-msgs = []
-rawmsgs = []
+rawmsgs = 'foo bar baz qux quux corge grault garply waldo fred'.split()
+msgs = map(lambda x:ircmsgs.privmsg('#channel', x), rawmsgs)
 
 class IrcMsgQueueTestCase(SupyTestCase):
     mode = ircmsgs.op('#foo', 'jemfinch')
@@ -258,8 +256,7 @@ class IrcStateTestCase(SupyTestCase):
         self.failUnless(st.channels['#foo'].isOp('baz'))
 
     def testHistory(self):
-        if len(msgs) < 10:
-            return
+        assert len(msgs) >= 10
         maxHistoryLength = conf.supybot.protocols.irc.maxHistoryLength
         with maxHistoryLength.context(10):
             state = irclib.IrcState()
@@ -272,6 +269,10 @@ class IrcStateTestCase(SupyTestCase):
             self.assertEqual(len(state.history), maxHistoryLength())
             self.assertEqual(list(state.history),
                              msgs[len(msgs) - maxHistoryLength():])
+            with maxHistoryLength.context(5):
+                self.assertEqual(len(state.history), maxHistoryLength())
+                self.assertEqual(list(state.history),
+                                 msgs[len(msgs) - maxHistoryLength():])
 
     def testWasteland005(self):
         state = irclib.IrcState()