diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index 5fc5b4a45844..ae55c2c786a7 100644
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -447,8 +447,8 @@ class InstanceEvents(object):
         def _create_or_get_event():
             if instance.uuid not in self._events:
                 self._events.setdefault(instance.uuid, {})
-                return self._events[instance.uuid].setdefault(
-                    event_name, eventlet.event.Event())
+            return self._events[instance.uuid].setdefault(
+                event_name, eventlet.event.Event())
         LOG.debug(_('Preparing to wait for external event %(event)s'),
                   {'event': event_name}, instance=instance)
         return _create_or_get_event()
diff --git a/nova/tests/compute/test_compute_mgr.py b/nova/tests/compute/test_compute_mgr.py
index d787da2aaf7f..ec5fdfba4f73 100644
--- a/nova/tests/compute/test_compute_mgr.py
+++ b/nova/tests/compute/test_compute_mgr.py
@@ -1013,6 +1013,22 @@ class ComputeManagerUnitTestCase(test.NoDBTestCase):
             self.compute.instance_events._events['foo']['test-event'])
         self.assertTrue(hasattr(result, 'send'))
 
+    def test_prepare_for_instance_event_again(self):
+        inst_obj = instance_obj.Instance(uuid='foo')
+        self.compute.instance_events.prepare_for_instance_event(
+            inst_obj, 'test-event')
+        # A second attempt will avoid creating a new list; make sure we
+        # get the current list
+        result = self.compute.instance_events.prepare_for_instance_event(
+            inst_obj, 'test-event')
+        self.assertIn('foo', self.compute.instance_events._events)
+        self.assertIn('test-event',
+                      self.compute.instance_events._events['foo'])
+        self.assertEqual(
+            result,
+            self.compute.instance_events._events['foo']['test-event'])
+        self.assertTrue(hasattr(result, 'send'))
+
     def test_process_instance_event(self):
         event = eventlet_event.Event()
         self.compute.instance_events._events = {