diff --git a/heat/engine/service.py b/heat/engine/service.py
index eabcee294..5ece16b99 100644
--- a/heat/engine/service.py
+++ b/heat/engine/service.py
@@ -191,7 +191,7 @@ class ThreadGroupManager(object):
                 eventlet.sleep()
 
     def send(self, stack_id, message):
-        for event in self.events.get(stack_id, []):
+        for event in self.events.pop(stack_id, []):
             event.send(message)