diff --git a/py/selenium/webdriver/remote/remote_connection.py b/py/selenium/webdriver/remote/remote_connection.py
index 1951d087540de..87d2917f2e0a5 100644
--- a/py/selenium/webdriver/remote/remote_connection.py
+++ b/py/selenium/webdriver/remote/remote_connection.py
@@ -513,7 +513,8 @@ def _request(self, method, url, body=None):
             else:
                 request = Request(url, data=body.encode('utf-8'), method=method)
 
-            request.headers.update(headers)
+            for key, val in headers.items():
+                request.add_header(key, val)
 
             if password_manager:
                 opener = url_request.build_opener(url_request.HTTPRedirectHandler(),
diff --git a/py/test/unit/selenium/webdriver/remote/test_remote_connection.py b/py/test/unit/selenium/webdriver/remote/test_remote_connection.py
index ddf30da858064..a4ab1d41d93b9 100644
--- a/py/test/unit/selenium/webdriver/remote/test_remote_connection.py
+++ b/py/test/unit/selenium/webdriver/remote/test_remote_connection.py
@@ -63,7 +63,8 @@ def getheader(self, *args, **kwargs):
 
 
 def test_remote_connection_adds_connection_headers_from_get_remote_connection_headers(mocker):
-    test_headers = {'FOO': 'bar'}
+    test_headers = {'FOO': 'bar', 'Content-Type': 'json'}
+    expected_request_headers = {'Foo': 'bar', 'Content-type': 'json'}
 
     # Stub out the get_remote_connection_headers method to return something testable
     mocker.patch(
@@ -77,7 +78,7 @@ def test_remote_connection_adds_connection_headers_from_get_remote_connection_he
         mock_open = mocker.patch('urllib2.OpenerDirector.open')
 
     def assert_header_added(request, timeout):
-        assert request.headers == test_headers
+        assert request.headers == expected_request_headers
         return MockResponse()
 
     mock_open.side_effect = assert_header_added