diff --git a/mitogen/core.py b/mitogen/core.py
index 3990819f..1f5ad0a9 100644
--- a/mitogen/core.py
+++ b/mitogen/core.py
@@ -1949,15 +1949,60 @@ class Broker(object):
         return 'Broker(%#x)' % (id(self),)
 
 
+class Dispatcher(object):
+    def __init__(self, econtext):
+        self.econtext = econtext
+        self.recv = Receiver(router=econtext.router,
+                             handle=CALL_FUNCTION,
+                             policy=has_parent_authority)
+        listen(econtext.broker, 'shutdown', self._on_broker_shutdown)
+
+    def _on_broker_shutdown(self):
+        self.recv.close()
+
+    def _dispatch_one(self, msg):
+        data = msg.unpickle(throw=False)
+        _v and LOG.debug('_dispatch_one(%r)', data)
+
+        modname, klass, func, args, kwargs = data
+        obj = import_module(modname)
+        if klass:
+            obj = getattr(obj, klass)
+        fn = getattr(obj, func)
+        if getattr(fn, 'mitogen_takes_econtext', None):
+            kwargs.setdefault('econtext', self.econtext)
+        if getattr(fn, 'mitogen_takes_router', None):
+            kwargs.setdefault('router', self.econtext.router)
+        return fn(*args, **kwargs)
+
+    def _dispatch_calls(self):
+        for msg in self.recv:
+            try:
+                ret = self._dispatch_one(msg)
+                _v and LOG.debug('_dispatch_calls: %r -> %r', msg, ret)
+                if msg.reply_to:
+                    msg.reply(ret)
+            except Exception:
+                e = sys.exc_info()[1]
+                if msg.reply_to:
+                    _v and LOG.debug('_dispatch_calls: %s', e)
+                    msg.reply(CallError(e))
+                else:
+                    LOG.exception('_dispatch_calls: %r', msg)
+
+    def run(self):
+        if self.econtext.config.get('on_start'):
+            self.econtext.config['on_start'](self)
+
+        _profile_hook('main', self._dispatch_calls)
+
+
 class ExternalContext(object):
     detached = False
 
     def __init__(self, config):
         self.config = config
 
-    def _on_broker_shutdown(self):
-        self.recv.close()
-
     def _on_broker_exit(self):
         if not self.config['profiling']:
             os.kill(os.getpid(), signal.SIGTERM)
@@ -2041,16 +2086,12 @@ class ExternalContext(object):
 
         in_fd = self.config.get('in_fd', 100)
         out_fd = self.config.get('out_fd', 1)
-        self.recv = Receiver(router=self.router,
-                             handle=CALL_FUNCTION,
-                             policy=has_parent_authority)
         self.stream = Stream(self.router, parent_id)
         self.stream.name = 'parent'
         self.stream.accept(in_fd, out_fd)
         self.stream.receive_side.keep_alive = False
 
         listen(self.stream, 'disconnect', self._on_parent_disconnect)
-        listen(self.broker, 'shutdown', self._on_broker_shutdown)
         listen(self.broker, 'exit', self._on_broker_exit)
 
         os.close(in_fd)
@@ -2148,40 +2189,6 @@ class ExternalContext(object):
         # Reopen with line buffering.
         sys.stdout = os.fdopen(1, 'w', 1)
 
-    def _dispatch_one(self, msg):
-        data = msg.unpickle(throw=False)
-        _v and LOG.debug('_dispatch_calls(%r)', data)
-
-        modname, klass, func, args, kwargs = data
-        obj = import_module(modname)
-        if klass:
-            obj = getattr(obj, klass)
-        fn = getattr(obj, func)
-        if getattr(fn, 'mitogen_takes_econtext', None):
-            kwargs.setdefault('econtext', self)
-        if getattr(fn, 'mitogen_takes_router', None):
-            kwargs.setdefault('router', self.router)
-        return fn(*args, **kwargs)
-
-    def _dispatch_calls(self):
-        if self.config.get('on_start'):
-            self.config['on_start'](self)
-
-        for msg in self.recv:
-            try:
-                ret = self._dispatch_one(msg)
-                _v and LOG.debug('_dispatch_calls: %r -> %r', msg, ret)
-                if msg.reply_to:
-                    msg.reply(ret)
-            except Exception:
-                e = sys.exc_info()[1]
-                if msg.reply_to:
-                    _v and LOG.debug('_dispatch_calls: %s', e)
-                    msg.reply(CallError(e))
-                else:
-                    LOG.exception('_dispatch_calls: %r', msg)
-        self.dispatch_stopped = True
-
     def main(self):
         self._setup_master()
         try:
@@ -2203,7 +2210,8 @@ class ExternalContext(object):
                                  self.parent, mitogen.context_id, os.getpid())
                 _v and LOG.debug('Recovered sys.executable: %r', sys.executable)
 
-                _profile_hook('main', self._dispatch_calls)
+                self.dispatcher = Dispatcher(self)
+                self.dispatcher.run()
                 _v and LOG.debug('ExternalContext.main() normal exit')
             except KeyboardInterrupt:
                 LOG.debug('KeyboardInterrupt received, exiting gracefully.')