diff --git a/swift/proxy/controllers/base.py b/swift/proxy/controllers/base.py
index d406540dc7..200e9682ff 100644
--- a/swift/proxy/controllers/base.py
+++ b/swift/proxy/controllers/base.py
@@ -728,8 +728,8 @@ class Controller(object):
             resp.status = HTTP_UNAUTHORIZED
             return resp  # CORS preflight request that isn't valid
         headers['access-control-allow-origin'] = req_origin_value
-        if cors.get('max_age', None) is not None:
-            headers['access-control-max-age'] = '%d' % cors.get('max_age')
+        if cors.get('max_age') is not None:
+            headers['access-control-max-age'] = cors.get('max_age')
         headers['access-control-allow-methods'] = ', '.join(
             self.allowed_methods)
         if cors.get('allow_headers'):
diff --git a/test/unit/proxy/test_server.py b/test/unit/proxy/test_server.py
index 6e05364735..089ce46859 100755
--- a/test/unit/proxy/test_server.py
+++ b/test/unit/proxy/test_server.py
@@ -3535,7 +3535,7 @@ class TestObjectController(unittest.TestCase):
                     'cors': {
                         'allow_origin': 'http://foo.bar:8080 https://foo.bar',
                         'allow_headers': 'x-foo',
-                        'max_age': 999,
+                        'max_age': '999',
                     }
                 }
             controller.container_info = my_container_info
@@ -3595,7 +3595,7 @@ class TestObjectController(unittest.TestCase):
                     'cors': {
                         'allow_origin': '*',
                         'allow_headers': 'x-foo',
-                        'max_age': 999,
+                        'max_age': '999',
                     }
                 }
             controller.container_info = my_container_info_wildcard
@@ -4141,7 +4141,7 @@ class TestContainerController(unittest.TestCase):
                     'cors': {
                         'allow_origin': 'http://foo.bar:8080 https://foo.bar',
                         'allow_headers': 'x-foo',
-                        'max_age': 999,
+                        'max_age': '999',
                     }
                 }
             controller.container_info = my_container_info
@@ -4202,7 +4202,7 @@ class TestContainerController(unittest.TestCase):
                     'cors': {
                         'allow_origin': '*',
                         'allow_headers': 'x-foo',
-                        'max_age': 999,
+                        'max_age': '999',
                     }
                 }
             controller.container_info = my_container_info_wildcard