diff -r ce9881eecfb4 Lib/http/client.py
--- a/Lib/http/client.py	Thu Nov 27 22:14:30 2014 +0200
+++ b/Lib/http/client.py	Fri Nov 28 14:36:23 2014 -0800
@@ -835,8 +835,7 @@
         if self.sock:
             raise RuntimeError("Can't set up tunnel for established connection")
 
-        self._tunnel_host = host
-        self._tunnel_port = port
+        self._tunnel_host, self._tunnel_port = self._get_hostport(host, port)
         if headers:
             self._tunnel_headers = headers
         else:
@@ -866,9 +865,8 @@
         self.debuglevel = level
 
     def _tunnel(self):
-        (host, port) = self._get_hostport(self._tunnel_host,
-                                          self._tunnel_port)
-        connect_str = "CONNECT %s:%d HTTP/1.0\r\n" % (host, port)
+        connect_str = "CONNECT %s:%d HTTP/1.0\r\n" % (self._tunnel_host,
+            self._tunnel_port)
         connect_bytes = connect_str.encode("ascii")
         self.send(connect_bytes)
         for header, value in self._tunnel_headers.items():
diff -r ce9881eecfb4 Lib/test/test_httplib.py
--- a/Lib/test/test_httplib.py	Thu Nov 27 22:14:30 2014 +0200
+++ b/Lib/test/test_httplib.py	Fri Nov 28 14:36:23 2014 -0800
@@ -4,6 +4,7 @@
 import os
 import array
 import socket
+import types
 
 import unittest
 TestCase = unittest.TestCase
@@ -1261,7 +1262,19 @@
         # But if we close the connection, we're good
         conn.close()
         conn.set_tunnel('destination.com')
+        conn.connect()
+
+        def patched_sendall(inst, data):
+            inst.sendall_calls += 1
+            inst.data += data
+            # issue22095
+            self.assertTrue(b'Host: destination.com:None' not in
+                conn.sock.data)
+
+        _sendall = conn.sock.sendall
+        conn.sock.sendall = types.MethodType(patched_sendall, conn.sock)
         conn.request('HEAD', '/', '')
+        conn.sock.sendall = _sendall
 
         self.assertEqual(conn.sock.host, 'proxy.com')
         self.assertEqual(conn.sock.port, 80)