diff --git a/oslo/messaging/notify/_impl_messaging.py b/oslo/messaging/notify/_impl_messaging.py
index ca0d4d10e..d422fbd6e 100644
--- a/oslo/messaging/notify/_impl_messaging.py
+++ b/oslo/messaging/notify/_impl_messaging.py
@@ -39,6 +39,7 @@ class MessagingDriver(notifier._Driver):
         self.envelope = envelope
 
     def notify(self, ctxt, message, priority):
+        priority = priority.lower()
         for topic in self.topics:
             target = messaging.Target(topic='%s.%s' % (topic, priority))
             try: