diff --git a/commands/partwhen.py b/commands/partwhen.py
new file mode 100644
index 0000000..77145a5
--- /dev/null
+++ b/commands/partwhen.py
@@ -0,0 +1,131 @@
+# -*- coding: utf-8  -*-
+#
+# Copyright (C) 2021 Ben Kurtovic <ben.kurtovic@gmail.com>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import base64
+import cPickle as pickle
+import re
+
+from earwigbot.commands import Command
+from earwigbot.config.permissions import User
+
+class PartWhen(Command):
+    """Ask the bot to part the channel when a condition is met."""
+    name = "partwhen"
+    commands = ["partwhen", "unpartwhen"]
+    hooks = ["join", "msg"]
+
+    def setup(self):
+        self._conds = self._load_conditions()
+
+    def check(self, data):
+        if data.is_command and data.command in self.commands:
+            return True
+        try:
+            if data.line[1] == "JOIN":
+                if data.chan in self._conds and "join" in self._conds[data.chan]:
+                    return True
+        except IndexError:
+            pass
+        return False
+
+    def process(self, data):
+        if data.line[1] == "JOIN":
+            self._handle_join(data)
+            return
+
+        if not self.config.irc["permissions"].is_admin(data):
+            self.reply(data, "You must be a bot admin to use this command.")
+            return
+
+        channel = data.chan
+        args = data.args
+        if args and args[0].startswith("#"):
+            # "!partwhen #channel <event> <args>..."
+            channel = args[0]
+            args = args[1:]
+
+        if data.command == "unpartwhen":
+            if self._conds.get(channel):
+                del self._conds[channel]
+                self._save_conditions()
+                self.reply(data, "Cleared part conditions for {0}.".format(
+                    "this channel" if channel == data.chan else channel))
+            else:
+                self.reply(data, "No part conditions set.")
+            return
+
+        if not args:
+            conds = self._conds.get(channel, {})
+            existing = "; ".join("{0} {1}".format(cond, ", ".join(str(user) for user in users))
+                                 for cond, users in conds.iteritems())
+            if existing:
+                status = "Current part conditions: {0}.".format(existing)
+            else:
+                status = "No part conditions set for {0}.".format(
+                    "this channel" if channel == data.chan else channel)
+            self.reply(data, "{0} Usage: !{1} [<channel>] <event> <args>...".format(
+                status, data.command))
+            return
+
+        event = args[0]
+        args = args[1:]
+        if event == "join":
+            if not args:
+                self.reply(data, "Join event requires an argument for the user joining, "
+                                 "in nick!ident@host syntax.")
+                return
+            cond = args[0]
+            match = re.match(r"(.*?)!(.*?)@(.*?)$", cond)
+            if not match:
+                self.reply(data, "User join pattern is invalid; should use "
+                                 "nick!ident@host syntax.")
+                return
+            conds = self._conds.setdefault(channel, {}).setdefault("join", [])
+            conds.append(User(match.group(1), match.group(2), match.group(3)))
+            self._save_conditions()
+            self.reply(data, "Okay, I will leave {0} when {1} joins.".format(
+                "the channel" if channel == data.chan else channel, cond))
+        else:
+            self.reply(data, "Unknown event: {0} (valid events: join).".format(event))
+
+    def _handle_join(self, data):
+        user = User(data.nick, data.ident, data.host)
+        conds = self._conds.get(data.chan, {}).get("join", {})
+        for cond in conds:
+            if user in cond:
+                self.logger.info("Parting {0} because {1} met join condition {2}".format(
+                    data.chan, str(user), str(cond)))
+                self.part(data.chan, "Requested to leave when {0} joined".format(data.nick))
+                break
+
+    def _load_conditions(self):
+        permdb = self.config.irc["permissions"]
+        try:
+            raw = permdb.get_attr("command:partwhen", "data")
+        except KeyError:
+            return {}
+        return pickle.loads(base64.b64decode(raw))
+
+    def _save_conditions(self):
+        permdb = self.config.irc["permissions"]
+        raw = base64.b64encode(pickle.dumps(self._conds, pickle.HIGHEST_PROTOCOL))
+        permdb.set_attr("command:partwhen", "data", raw)
diff --git a/commands/rc_monitor.py b/commands/rc_monitor.py
index 3f28eff..19c4659 100644
--- a/commands/rc_monitor.py
+++ b/commands/rc_monitor.py
@@ -49,6 +49,7 @@ class RCMonitor(Command):
             log = ('Cannot use without a report channel set as '
                    'config.commands["{0}"]["channel"]')
             self.logger.warn(log.format(self.name))
+            return
 
         self._stats = {
             "start": datetime.utcnow(),