diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 064f0e8..d83ee2c 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -4434,6 +4434,37 @@
                 s.write(b'PHA')
                 self.assertIn(b'WRONG_SSL_VERSION', s.recv(1024))
 
+    def test_bpo37428_pha_cert_none(self):
+        # verify that post_handshake_auth does not implicitly enable cert
+        # validation.
+        hostname = SIGNED_CERTFILE_HOSTNAME
+        client_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
+        client_context.post_handshake_auth = True
+        client_context.load_cert_chain(SIGNED_CERTFILE)
+        # no cert validation and CA on client side
+        client_context.check_hostname = False
+        client_context.verify_mode = ssl.CERT_NONE
+
+        server_context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
+        server_context.load_cert_chain(SIGNED_CERTFILE)
+        server_context.load_verify_locations(SIGNING_CA)
+        server_context.post_handshake_auth = True
+        server_context.verify_mode = ssl.CERT_REQUIRED
+
+        server = ThreadedEchoServer(context=server_context, chatty=False)
+        with server:
+            with client_context.wrap_socket(socket.socket(),
+                                            server_hostname=hostname) as s:
+                s.connect((HOST, server.port))
+                s.write(b'HASCERT')
+                self.assertEqual(s.recv(1024), b'FALSE\n')
+                s.write(b'PHA')
+                self.assertEqual(s.recv(1024), b'OK\n')
+                s.write(b'HASCERT')
+                self.assertEqual(s.recv(1024), b'TRUE\n')
+                # server cert has not been validated
+                self.assertEqual(s.getpeercert(), {})
+
 
 HAS_KEYLOG = hasattr(ssl.SSLContext, 'keylog_filename')
 requires_keylog = unittest.skipUnless(