diff --git a/Lib/http/client.py b/Lib/http/client.py
index f273b03..bd092c2 100644
--- a/Lib/http/client.py
+++ b/Lib/http/client.py
@@ -873,6 +873,13 @@
                         host_enc = self.host.encode("ascii")
                     except UnicodeEncodeError:
                         host_enc = self.host.encode("idna")
+
+                    # As per RFC 273, IPv6 address should be wrapped with []
+                    # when used as Host header
+
+                    if self.host.find(':') >= 0:
+                        host_enc = b'[' + host_enc + b']'
+
                     if self.port == self.default_port:
                         self.putheader('Host', host_enc)
                     else:
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index 6b703dd..ee28316 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -96,6 +96,25 @@
         conn.putheader('Content-length', 42)
         self.assertTrue(b'Content-length: 42' in conn._buffer)
 
+    def test_ipv6host_header(self):
+        # Default host header on IPv6 transaction should wrapped by [] if
+        # its actual IPv6 address
+        expected = b'GET /foo HTTP/1.1\r\nHost: [2001::]:81\r\n' \
+                   b'Accept-Encoding: identity\r\n\r\n'
+        conn = client.HTTPConnection('[2001::]:81')
+        sock = FakeSocket('')
+        conn.sock = sock
+        conn.request('GET', '/foo')
+        self.assertTrue(sock.data.startswith(expected))
+
+        expected = b'GET /foo HTTP/1.1\r\nHost: [2001:102A::]\r\n' \
+                   b'Accept-Encoding: identity\r\n\r\n'
+        conn = client.HTTPConnection('[2001:102A::]')
+        sock = FakeSocket('')
+        conn.sock = sock
+        conn.request('GET', '/foo')
+        self.assertTrue(sock.data.startswith(expected))
+
 
 class BasicTest(TestCase):
     def test_status_lines(self):