diff --git a/glance_store/_drivers/vmware_datastore.py b/glance_store/_drivers/vmware_datastore.py
index 0c3c4d8..a996328 100644
--- a/glance_store/_drivers/vmware_datastore.py
+++ b/glance_store/_drivers/vmware_datastore.py
@@ -558,7 +558,7 @@ class Store(glance_store.Store):
         image_file = _Reader(image_file, verifier)
         headers = {}
         if image_size > 0:
-            headers.update({'Content-Length': image_size})
+            headers.update({'Content-Length': six.text_type(image_size)})
             data = image_file
         else:
             data = utils.chunkiter(image_file, CHUNKSIZE)
diff --git a/glance_store/tests/unit/test_vmware_store.py b/glance_store/tests/unit/test_vmware_store.py
index 569309d..c77b9fd 100644
--- a/glance_store/tests/unit/test_vmware_store.py
+++ b/glance_store/tests/unit/test_vmware_store.py
@@ -131,10 +131,12 @@ class TestStore(base.StoreBaseTest,
             HttpConn.return_value = utils.fake_response(status_code=404)
             self.assertRaises(exceptions.NotFound, self.store.get, loc)
 
+    @mock.patch.object(vm_store.Store, '_build_vim_cookie_header')
     @mock.patch.object(vm_store.Store, 'select_datastore')
     @mock.patch.object(vm_store._Reader, 'size')
     @mock.patch.object(api, 'VMwareAPISession')
-    def test_add(self, fake_api_session, fake_size, fake_select_datastore):
+    def test_add(self, fake_api_session, fake_size, fake_select_datastore,
+                 fake_cookie):
         """Test that we can add an image via the VMware backend."""
         fake_select_datastore.return_value = self.store.datastores[0][0]
         expected_image_id = str(uuid.uuid4())
@@ -143,6 +145,10 @@ class TestStore(base.StoreBaseTest,
         hash_code = hashlib.md5(expected_contents)
         expected_checksum = hash_code.hexdigest()
         fake_size.__get__ = mock.Mock(return_value=expected_size)
+        expected_cookie = 'vmware_soap_session=fake-uuid'
+        fake_cookie.return_value = expected_cookie
+        expected_headers = {'Content-Length': six.text_type(expected_size),
+                            'Cookie': expected_cookie}
         with mock.patch('hashlib.md5') as md5:
             md5.return_value = hash_code
             expected_location = format_location(
@@ -156,6 +162,8 @@ class TestStore(base.StoreBaseTest,
                 location, size, checksum, _ = self.store.add(expected_image_id,
                                                              image,
                                                              expected_size)
+                _, kwargs = HttpConn.call_args
+                self.assertEqual(expected_headers, kwargs['headers'])
         self.assertEqual(utils.sort_url_by_qs_keys(expected_location),
                          utils.sort_url_by_qs_keys(location))
         self.assertEqual(expected_size, size)