diff --git a/glance/api/v2/image_data.py b/glance/api/v2/image_data.py
index 2fffbc7a5c..3a31d04ef3 100644
--- a/glance/api/v2/image_data.py
+++ b/glance/api/v2/image_data.py
@@ -43,9 +43,12 @@ class ImageDataController(base.Controller):
 
     def upload(self, req, image_id, data):
         self._get_image(req.context, image_id)
-        size = len(data)
-        location, size, checksum = self.store_api.add_to_backend(
-                'file', image_id, data, size)
+        try:
+            location, size, checksum = self.store_api.add_to_backend(
+                    'file', image_id, data, len(data))
+        except exception.Duplicate:
+            raise webob.exc.HTTPConflict()
+
         self.db_api.image_update(req.context, image_id, {'location': location})
 
     def download(self, req, image_id):
diff --git a/glance/tests/functional/v2/test_images.py b/glance/tests/functional/v2/test_images.py
index 04bdae0719..20bbfb1c1f 100644
--- a/glance/tests/functional/v2/test_images.py
+++ b/glance/tests/functional/v2/test_images.py
@@ -140,3 +140,36 @@ class TestImages(functional.FunctionalTest):
         self.assertEqual(0, len(images))
 
         self.stop_servers()
+
+    def test_upload_duplicate_data(self):
+        # Create an image
+        path = self._url('/v2/images')
+        headers = self._headers({'content-type': 'application/json'})
+        data = json.dumps({'name': 'image-1'})
+        response = requests.post(path, headers=headers, data=data)
+        self.assertEqual(200, response.status_code)
+
+        # Returned image entity should have a generated id
+        image = json.loads(response.text)['image']
+        image_id = image['id']
+
+        # Upload some image data
+        path = self._url('/v2/images/%s/file' % image_id)
+        headers = self._headers()
+        response = requests.put(path, headers=headers, data='ZZZZZ')
+        self.assertEqual(200, response.status_code)
+
+        # Uploading duplicate data should be rejected with a 409
+        path = self._url('/v2/images/%s/file' % image_id)
+        headers = self._headers()
+        response = requests.put(path, headers=headers, data='XXX')
+        self.assertEqual(409, response.status_code)
+
+        # Data should not have been overwritten
+        path = self._url('/v2/images/%s/file' % image_id)
+        headers = self._headers()
+        response = requests.get(path, headers=headers)
+        self.assertEqual(200, response.status_code)
+        self.assertEqual(response.text, 'ZZZZZ')
+
+        self.stop_servers()
diff --git a/glance/tests/unit/utils.py b/glance/tests/unit/utils.py
index 27db2ea267..dfbcad1e89 100644
--- a/glance/tests/unit/utils.py
+++ b/glance/tests/unit/utils.py
@@ -52,7 +52,7 @@ class FakeDB(object):
 
     def __init__(self):
         self.images = {
-            UUID1: self._image_format(UUID1, location='1'),
+            UUID1: self._image_format(UUID1, location=UUID1),
             UUID2: self._image_format(UUID2),
         }
         self.members = {
@@ -180,8 +180,7 @@ class FakeDB(object):
 class FakeStoreAPI(object):
     def __init__(self):
         self.data = {
-            '1': ('XXX', 3),
-            '2': ('FFFFF', 5),
+            UUID1: ('XXX', 3),
         }
 
     def create_stores(self, conf):
@@ -199,7 +198,8 @@ class FakeStoreAPI(object):
         return self.get_from_backend(location)[1]
 
     def add_to_backend(self, scheme, image_id, data, size):
-        location = utils.generate_uuid()
-        self.data[location] = (data, size)
+        if image_id in self.data:
+            raise exception.Duplicate()
+        self.data[image_id] = (data, size)
         checksum = 'Z'
-        return (location, size, checksum)
+        return (image_id, size, checksum)
diff --git a/glance/tests/unit/v2/test_image_data_resource.py b/glance/tests/unit/v2/test_image_data_resource.py
index e026b45dd7..0838006ad4 100644
--- a/glance/tests/unit/v2/test_image_data_resource.py
+++ b/glance/tests/unit/v2/test_image_data_resource.py
@@ -63,6 +63,11 @@ class TestImagesController(unittest.TestCase):
         self.assertRaises(webob.exc.HTTPNotFound, self.controller.upload,
                           request, utils.generate_uuid(), 'YYYY')
 
+    def test_upload_data_exists(self):
+        request = test_utils.FakeRequest()
+        self.assertRaises(webob.exc.HTTPConflict, self.controller.upload,
+                          request, test_utils.UUID1, 'YYYY')
+
 
 class TestImageDataDeserializer(unittest.TestCase):
     def setUp(self):
diff --git a/glance/tests/unit/v2/test_images_resource.py b/glance/tests/unit/v2/test_images_resource.py
index 85424b1ea1..17fb106959 100644
--- a/glance/tests/unit/v2/test_images_resource.py
+++ b/glance/tests/unit/v2/test_images_resource.py
@@ -79,7 +79,7 @@ class TestImagesController(unittest.TestCase):
         expected = {
             'name': 'image-2',
             'owner': test_utils.TENANT1,
-            'location': '1',
+            'location': test_utils.UUID1,
             'status': 'queued',
         }
         self.assertEqual(expected, output)