diff --git a/scrapy/core/downloader/handlers/http11.py b/scrapy/core/downloader/handlers/http11.py
index d81093a9f..729b80b05 100644
--- a/scrapy/core/downloader/handlers/http11.py
+++ b/scrapy/core/downloader/handlers/http11.py
@@ -78,7 +78,7 @@ class TunnelingTCP4ClientEndpoint(TCP4ClientEndpoint):
     for it.
     """
 
-    _responseMatcher = re.compile('HTTP/1\.. 200')
+    _responseMatcher = re.compile(b'HTTP/1\.. 200')
 
     def __init__(self, reactor, host, port, proxyConf, contextFactory,
                  timeout=30, bindAddress=None):
@@ -92,11 +92,15 @@ class TunnelingTCP4ClientEndpoint(TCP4ClientEndpoint):
 
     def requestTunnel(self, protocol):
         """Asks the proxy to open a tunnel."""
-        tunnelReq = 'CONNECT %s:%s HTTP/1.1\r\n' % (self._tunneledHost,
-                                                  self._tunneledPort)
+        tunnelReq = (
+            b'CONNECT ' +
+            to_bytes(self._tunneledHost, encoding='ascii') + b':' +
+            to_bytes(str(self._tunneledPort)) +
+            b' HTTP/1.1\r\n')
         if self._proxyAuthHeader:
-            tunnelReq += 'Proxy-Authorization: %s\r\n' % self._proxyAuthHeader
-        tunnelReq += '\r\n'
+            tunnelReq += \
+                b'Proxy-Authorization: ' + self._proxyAuthHeader + b'\r\n'
+        tunnelReq += b'\r\n'
         protocol.transport.write(tunnelReq)
         self._protocolDataReceived = protocol.dataReceived
         protocol.dataReceived = self.processProxyResponse
diff --git a/tests/test_downloader_handlers.py b/tests/test_downloader_handlers.py
index 999fa4c0a..2d6c05741 100644
--- a/tests/test_downloader_handlers.py
+++ b/tests/test_downloader_handlers.py
@@ -388,6 +388,16 @@ class HttpProxyTestCase(unittest.TestCase):
         request = Request('https://example.com', meta={'proxy': http_proxy})
         return self.download_request(request, Spider('foo')).addCallback(_test)
 
+    @defer.inlineCallbacks
+    def test_download_with_proxy_https_timeout(self):
+        http_proxy = self.getURL('')
+        domain = 'https://no-such-domain.nosuch'
+        request = Request(
+            domain, meta={'proxy': http_proxy, 'download_timeout': 0.2})
+        d = self.download_request(request, Spider('foo'))
+        timeout = yield self.assertFailure(d, error.TimeoutError)
+        self.assertIn(domain, timeout.osError)
+
     def test_download_without_proxy(self):
         def _test(response):
             self.assertEquals(response.status, 200)