diff --git a/requirements.txt b/requirements.txt
index 7c52c14d0..0df9a558c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-Twisted>=10.0.0,<14.0.0
+Twisted>=10.0.0
 lxml
 pyOpenSSL
 cssselect>=0.9
diff --git a/scrapy/core/downloader/handlers/http11.py b/scrapy/core/downloader/handlers/http11.py
index de3cc8756..52eb35eba 100644
--- a/scrapy/core/downloader/handlers/http11.py
+++ b/scrapy/core/downloader/handlers/http11.py
@@ -118,6 +118,7 @@ class TunnelingAgent(Agent):
         super(TunnelingAgent, self).__init__(reactor, contextFactory,
             connectTimeout, bindAddress, pool)
         self._proxyConf = proxyConf
+        self._contextFactory = contextFactory
 
     def _getEndpoint(self, scheme, host, port):
         return TunnelingTCP4ClientEndpoint(self._reactor, host, port,
diff --git a/setup.py b/setup.py
index 1d6c444d0..6efe64074 100644
--- a/setup.py
+++ b/setup.py
@@ -123,7 +123,7 @@ except ImportError:
     from distutils.core import setup
 else:
     setup_args['install_requires'] = [
-        'Twisted>=10.0.0,<14.0.0',
+        'Twisted>=10.0.0',
         'w3lib>=1.2',
         'queuelib',
         'lxml',