diff --git a/glance/artifacts/location.py b/glance/artifacts/location.py
index d63be7cf1e..3f7df74231 100644
--- a/glance/artifacts/location.py
+++ b/glance/artifacts/location.py
@@ -136,6 +136,8 @@ class ArtifactBlobProxy(proxy.ArtifactBlob):
             LOG.error(msg)
 
     def upload_to_store(self, data, size):
+        if size is None:  # NOTE(ativelkov): None is "unknown size"
+            size = 0
         location, ret_size, checksum, loc_meta = self.store_api.add_to_backend(
             CONF,
             self.blob.item_key,
diff --git a/glance/tests/functional/artifacts/test_artifacts.py b/glance/tests/functional/artifacts/test_artifacts.py
index 1aa199577b..45175e4670 100644
--- a/glance/tests/functional/artifacts/test_artifacts.py
+++ b/glance/tests/functional/artifacts/test_artifacts.py
@@ -969,6 +969,29 @@ paste.filter_factory = glance.tests.utils:FakeAuthMiddleware.factory
             '/withblob/%s/blob1/download' % art['id'])
         self.assertEqual('ZZZZZ', data)
 
+    def test_file_w_unknown_size(self):
+        # Upload and download data provided by an iterator, thus without
+        # knowing the length in advance
+        art = self._create_artifact('withblob')
+        artifact_id = art['id']
+
+        def iterate_string(val):
+            for char in val:
+                yield char
+
+        headers = self._headers({'Content-Type': 'application/octet-stream'})
+        self._check_artifact_post('/withblob/v1/%s/blob1' % art['id'],
+                                  headers=headers,
+                                  data=iterate_string('ZZZZZ'), status=200)
+
+        art = self._check_artifact_get('/withblob/%s' % artifact_id)
+        self.assertEqual(artifact_id, art['id'])
+        self.assertIn('download_link', art['blob1'])
+
+        data = self._check_artifact_get(
+            '/withblob/%s/blob1/download' % art['id'])
+        self.assertEqual('ZZZZZ', data)
+
     def test_limit(self):
         artifact_data = {'name': 'artifact-1',
                          'version': '12'}