diff --git a/nova/db/sqlalchemy/api.py b/nova/db/sqlalchemy/api.py
index 3ddc41adb472..1c9a03e1dbc8 100644
--- a/nova/db/sqlalchemy/api.py
+++ b/nova/db/sqlalchemy/api.py
@@ -5413,7 +5413,6 @@ def aggregate_update(context, aggregate_id, values):
 
         aggregate.update(values)
         aggregate.save(session=session)
-        values['metadata'] = metadata
         return aggregate_get(context, aggregate.id)
     else:
         raise exception.AggregateNotFound(aggregate_id=aggregate_id)
diff --git a/nova/tests/unit/db/test_db_api.py b/nova/tests/unit/db/test_db_api.py
index e77a3daccc86..ced107f281f5 100644
--- a/nova/tests/unit/db/test_db_api.py
+++ b/nova/tests/unit/db/test_db_api.py
@@ -689,11 +689,13 @@ class AggregateDBApiTestCase(test.TestCase):
         values = _get_fake_aggr_values()
         values['metadata'] = _get_fake_aggr_metadata()
         values['availability_zone'] = 'different_avail_zone'
+        expected_metadata = copy.deepcopy(values['metadata'])
+        expected_metadata['availability_zone'] = values['availability_zone']
         db.aggregate_update(ctxt, result['id'], values)
-        expected = db.aggregate_metadata_get(ctxt, result['id'])
+        metadata = db.aggregate_metadata_get(ctxt, result['id'])
         updated = db.aggregate_get(ctxt, result['id'])
-        self.assertThat(values['metadata'],
-                        matchers.DictMatches(expected))
+        self.assertThat(metadata,
+                        matchers.DictMatches(expected_metadata))
         self.assertNotEqual(result['availability_zone'],
                             updated['availability_zone'])
 
@@ -703,9 +705,10 @@ class AggregateDBApiTestCase(test.TestCase):
         values = _get_fake_aggr_values()
         values['metadata'] = _get_fake_aggr_metadata()
         values['metadata']['fake_key1'] = 'foo'
+        expected_metadata = copy.deepcopy(values['metadata'])
         db.aggregate_update(ctxt, result['id'], values)
-        expected = db.aggregate_metadata_get(ctxt, result['id'])
-        self.assertThat(values['metadata'], matchers.DictMatches(expected))
+        metadata = db.aggregate_metadata_get(ctxt, result['id'])
+        self.assertThat(metadata, matchers.DictMatches(expected_metadata))
 
     def test_aggregate_update_zone_with_existing_metadata(self):
         ctxt = context.get_admin_context()