diff --git a/plugins/Conditional/plugin.py b/plugins/Conditional/plugin.py
index 0a1b14ea7..921e65732 100644
--- a/plugins/Conditional/plugin.py
+++ b/plugins/Conditional/plugin.py
@@ -35,6 +35,7 @@ import supybot.ircutils as ircutils
 import supybot.callbacks as callbacks
 
 import re
+import collections
 
 try:
     from supybot.i18n import PluginInternationalization
@@ -297,6 +298,45 @@ class Conditional(callbacks.Plugin):
         else:
             irc.reply('false')
     nle = wrap(nle, ['float', 'float'])
+
+    def iferror(self, irc, msg, args, testcommand, ifcommand, elsecommand):
+        """<testcommand> <ifcommand> <elsecommand>
+
+        Runs <ifcommand> if <testcommand> raises an error, runs <elsecommand>
+        otherwise.
+        """
+        tokens = callbacks.tokenize(testcommand)
+        InvalidCommand = collections.namedtuple('InvalidCommand',
+                'command')
+        replies = []
+        errors = []
+        class ErrorReportingProxy(self.Proxy):
+            def reply(self2, s, *args, **kwargs):
+                replies.append(s)
+            def error(self2, s, Raise=False, *args, **kwargs):
+                errors.append(s)
+                if Raise:
+                    raise ArgumentError
+            def _callInvalidCommands(self2):
+                errors.append(InvalidCommand(self2.args))
+            def evalArgs(self2):
+                # We don't want the replies in the nested command to
+                # be stored here.
+                super(ErrorReportingProxy, self2).evalArgs(withClass=self.Proxy)
+
+        try:
+            ErrorReportingProxy(irc.irc, msg, tokens)
+        except callbacks.ArgumentError as e:
+            pass
+        # TODO: do something with the results
+        if errors:
+            tokens = callbacks.tokenize(ifcommand)
+            self.Proxy(irc, msg, tokens)
+        else:
+            tokens = callbacks.tokenize(elsecommand)
+            self.Proxy(irc, msg, tokens)
+    iferror = wrap(iferror, ['something', 'something', 'something'])
+
 Condition = internationalizeDocstring(Conditional)
 
 Class = Conditional
diff --git a/plugins/Conditional/test.py b/plugins/Conditional/test.py
index a6fcd174e..562a324a0 100644
--- a/plugins/Conditional/test.py
+++ b/plugins/Conditional/test.py
@@ -145,5 +145,28 @@ class ConditionalTestCase(PluginTestCase):
         self.assertRegexp('nle 4 3', 'false')
         self.assertError('nle 3 4 5')
         self.assertError('nle 1 bla')
+
+    def testIferror(self):
+        self.assertResponse(
+                'iferror "echo hi" "foo" "bar"',
+                'Error: "bar" is not a valid command.')
+        self.assertResponse(
+                'iferror "echo hi" "echo 1 error" "echo 0 errors"',
+                '0 errors')
+        self.assertResponse(
+                'iferror "foobarbaz" "echo 1 error" "echo 0 errors"',
+                '1 error')
+        self.assertResponse(
+                'iferror "help foobarbaz" "echo 1 error" "echo 0 errors"',
+                '1 error')
+        self.assertResponse(
+                r'iferror "iferror \"help foobarbaz\" \"echo hi\" \"foobarbaz\"" '
+                r'"foo" "bar"',
+                'Error: "bar" is not a valid command.')
+        self.assertResponse(
+                r'iferror "iferror \"help foobarbaz\" \"echo hi\" \"foobarbaz\"" '
+                r'"echo 0 errors" "echo 1 error"',
+                '1 error')
+
         
 # vim:set shiftwidth=4 tabstop=4 expandtab textwidth=79:
diff --git a/src/callbacks.py b/src/callbacks.py
index 2bec92362..e198b54a6 100644
--- a/src/callbacks.py
+++ b/src/callbacks.py
@@ -659,7 +659,7 @@ class NestedCommandsIrcProxy(ReplyIrcProxy):
         else:
             self.prefixNick = conf.supybot.reply.withNickPrefix()
 
-    def evalArgs(self):
+    def evalArgs(self, withClass=None):
         while self.counter < len(self.args):
             self.repliedTo = False
             if isinstance(self.args[self.counter], minisix.string_types):
@@ -676,8 +676,9 @@ class NestedCommandsIrcProxy(ReplyIrcProxy):
                 # evaluating its args, it will call our reply method, which
                 # will subsequently call this function again, and we'll
                 # pick up where we left off via self.counter.
-                self.__class__(self, self.msg,
-                               self.args[self.counter], nested=self.nested+1)
+                cls = withClass or self.__class__
+                cls(self, self.msg, self.args[self.counter],
+                        nested=self.nested+1)
                 # We have to return here because the new NestedCommandsIrcProxy
                 # might not have called our reply method instantly, since
                 # its command might be threaded.  So (obviously) we can't