diff --git a/nova/compute/resource_tracker.py b/nova/compute/resource_tracker.py
index c6860a5d4b..0d3cd4fa67 100644
--- a/nova/compute/resource_tracker.py
+++ b/nova/compute/resource_tracker.py
@@ -824,9 +824,13 @@ class ResourceTracker(object):
             # filter to most recently updated migration for each instance:
             other_migration = filtered.get(uuid, None)
             # NOTE(claudiub): In Python 3, you cannot compare NoneTypes.
-            if (not other_migration or (
-                    migration.updated_at and other_migration.updated_at and
-                    migration.updated_at >= other_migration.updated_at)):
+            if other_migration:
+                om = other_migration
+                other_time = om.updated_at or om.created_at
+                migration_time = migration.updated_at or migration.created_at
+                if migration_time > other_time:
+                    filtered[uuid] = migration
+            else:
                 filtered[uuid] = migration
 
         for migration in filtered.values():
diff --git a/nova/tests/unit/compute/test_resource_tracker.py b/nova/tests/unit/compute/test_resource_tracker.py
index 0f713c88c2..211bad443e 100644
--- a/nova/tests/unit/compute/test_resource_tracker.py
+++ b/nova/tests/unit/compute/test_resource_tracker.py
@@ -2054,6 +2054,7 @@ class TestUpdateUsageFromMigrations(BaseTestCase):
         instance = objects.Instance(vm_state=vm_states.RESIZED,
                                     task_state=None)
         ts1 = timeutils.utcnow()
+        ts0 = ts1 - datetime.timedelta(seconds=10)
         ts2 = ts1 + datetime.timedelta(seconds=10)
 
         migrations = [
@@ -2062,6 +2063,7 @@ class TestUpdateUsageFromMigrations(BaseTestCase):
                               dest_compute=_HOSTNAME,
                               dest_node=_NODENAME,
                               instance_uuid=uuids.instance,
+                              created_at=ts0,
                               updated_at=ts1,
                               instance=instance),
             objects.Migration(source_compute=_HOSTNAME,
@@ -2069,6 +2071,7 @@ class TestUpdateUsageFromMigrations(BaseTestCase):
                               dest_compute=_HOSTNAME,
                               dest_node=_NODENAME,
                               instance_uuid=uuids.instance,
+                              created_at=ts0,
                               updated_at=ts2,
                               instance=instance)
         ]
@@ -2078,10 +2081,7 @@ class TestUpdateUsageFromMigrations(BaseTestCase):
         upd_mock.assert_called_once_with(mock.sentinel.ctx, instance, mig2)
 
         upd_mock.reset_mock()
-        mig1.updated_at = None
-
-        # For some reason, the code thinks None should always take
-        # precedence over any datetime in the updated_at attribute...
+        mig2.updated_at = None
         self.rt._update_usage_from_migrations(mock.sentinel.ctx, mig_list)
         upd_mock.assert_called_once_with(mock.sentinel.ctx, instance, mig1)