diff --git a/acme/acme/standalone.py b/acme/acme/standalone.py
index 8f604a439..501d239cb 100644
--- a/acme/acme/standalone.py
+++ b/acme/acme/standalone.py
@@ -4,6 +4,7 @@ import collections
 import functools
 import logging
 import os
+import socket
 import sys
 
 import six
@@ -52,18 +53,52 @@ class HTTPSServer(TLSServer, BaseHTTPServer.HTTPServer):
 
 
 class ACMEServerMixin:  # pylint: disable=old-style-class,no-init
-    """ACME server common settings mixin."""
+    """ACME server common settings mixin.
+
+    .. warning::
+       Subclasses have to init ``_stopped = False`` (it's not done here,
+       because of old-style classes madness).
+
+    """
     server_version = "ACME standalone client"
     allow_reuse_address = True
 
+    def serve_forever2(self):
+        """Serve forever, until other thread calls `shutdown2`."""
+        while not self._stopped:
+            self.handle_request()
+
+    def shutdown2(self):
+        """Shutdown server loop from `serve_forever2`."""
+        self._stopped = True
+
+        # dummy request to terminate last server_forever2.handle_request()
+        sock = socket.socket()
+        try:
+            sock.connect(self.socket.getsockname())
+        except socket.error:
+            pass  # thread is probably already finished
+        finally:
+            sock.close()
+
+        self.server_close()
+
 
 class ACMETLSServer(HTTPSServer, ACMEServerMixin):
     """ACME TLS Server."""
 
+    def __init__(self, *args, **kwargs):
+        self._stopped = False
+        HTTPSServer.__init__(self, *args, **kwargs)
+
 
 class ACMEServer(BaseHTTPServer.HTTPServer, ACMEServerMixin):
     """ACME Server (non-TLS)."""
 
+    def __init__(self, *args, **kwargs):
+        self._stopped = False
+        BaseHTTPServer.HTTPServer.__init__(self, *args, **kwargs)
+
 
 class SimpleHTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
     """SimpleHTTP challenge handler.
diff --git a/acme/acme/standalone_test.py b/acme/acme/standalone_test.py
index 794fb1a6e..9ff99f5ff 100644
--- a/acme/acme/standalone_test.py
+++ b/acme/acme/standalone_test.py
@@ -25,6 +25,26 @@ class TLSServerTest(unittest.TestCase):
         server.server_close()  # pylint: disable=no-member
 
 
+class ACMEServerMixinTest(unittest.TestCase):
+    """Tests for acme.standalone.ACMEServerMixin."""
+
+    def test_shutdown2_not_running(self):
+        from acme.standalone import ACMEServer
+        server = ACMEServer(("", 0), socketserver.BaseRequestHandler)
+        server.shutdown2()
+        server.shutdown2()
+
+
+class ACMEServerTest(unittest.TestCase):
+    """Test for acme.standalone.ACMEServer."""
+
+    def test_init(self):
+        from acme.standalone import ACMEServer
+        server = ACMEServer(("", 0), socketserver.BaseRequestHandler)
+        # pylint: disable=protected-access
+        self.assertFalse(server._stopped)
+
+
 class ACMESimpleHTTPTLSServerTestEndToEnd(unittest.TestCase):
     """End-to-end test for ACME TLS server with SimpleHTTP."""
 
@@ -45,12 +65,13 @@ class ACMESimpleHTTPTLSServerTestEndToEnd(unittest.TestCase):
         self.server = ACMETLSServer(('', 0), handler, certs=self.certs)
         self.server_thread = threading.Thread(
             # pylint: disable=no-member
-            target=self.server.handle_request)
+            target=self.server.serve_forever2)
         self.server_thread.start()
 
         self.port = self.server.socket.getsockname()[1]
 
     def tearDown(self):
+        self.server.shutdown2()
         self.server_thread.join()
 
     def test_index(self):
diff --git a/letsencrypt/plugins/standalone.py b/letsencrypt/plugins/standalone.py
index 5f2bc9292..071fdbf42 100644
--- a/letsencrypt/plugins/standalone.py
+++ b/letsencrypt/plugins/standalone.py
@@ -53,33 +53,15 @@ class ServerManager(object):
         except socket.error as error:
             errors.StandaloneBindError(error, port)
 
-        stop = threading.Event()
-        thread = threading.Thread(
-            target=self._serve,
-            args=(server, stop),
-        )
+        thread = threading.Thread(target=server.serve_forever2)
         thread.start()
-        self.servers[port] = (server, thread, stop)
+        self.servers[port] = (server, thread)
         return self.servers[port]
 
-    def _serve(self, server, stop):
-        while not stop.is_set():
-            server.handle_request()
-
     def stop(self, port):
         """Stop ACME server running on the specified ``port``."""
-        server, thread, stop = self.servers[port]
-        stop.set()
-
-        # dummy request to terminate last handle_request()
-        sock = socket.socket()
-        try:
-            sock.connect(server.socket.getsockname())
-        except socket.error:
-            pass  # thread is probably already finished
-        finally:
-            sock.close()
-
+        server, thread = self.servers[port]
+        server.shutdown2()
         thread.join()
         del self.servers[port]
 
@@ -170,7 +152,7 @@ class Authenticator(common.Plugin):
 
         for achall in achalls:
             if isinstance(achall, achallenges.SimpleHTTP):
-                server, _, _ = self.servers.run(self.config.simple_http_port, tls=tls)
+                server, _ = self.servers.run(self.config.simple_http_port, tls=tls)
                 response, validation = achall.gen_response_and_validation(tls=tls)
                 self.simple_http_resources.add(
                     acme_standalone.SimpleHTTPRequestHandler.SimpleHTTPResource(
@@ -179,7 +161,7 @@ class Authenticator(common.Plugin):
                 cert = self.simple_http_cert
                 domain = achall.domain
             else:  # DVSNI
-                server, _, _ = self.servers.run(self.config.dvsni_port, tls=True)
+                server, _ = self.servers.run(self.config.dvsni_port, tls=True)
                 response, cert, _ = achall.gen_cert_and_response(self.key)
                 domain = response.z_domain
             self.certs[domain] = (self.key, cert)
@@ -195,6 +177,6 @@ class Authenticator(common.Plugin):
             for achall in achalls:
                 if achall in server_achalls:
                     server_achalls.remove(achall)
-        for port, (server, _, _) in self.servers.items():
+        for port, (server, _) in self.servers.items():
             if not self.served[server]:
                 self.servers.stop(port)