diff --git a/src/tmp/wokkel/rsm.py b/src/tmp/wokkel/rsm.py
index e6cf6cd7..cc1eef1b 100644
--- a/src/tmp/wokkel/rsm.py
+++ b/src/tmp/wokkel/rsm.py
@@ -25,6 +25,7 @@ U{XEP-0059<http://xmpp.org/extensions/xep-0059.html>}.
 """
 
 from twisted.words.xish import domish
+from twisted.words.protocols.jabber import error
 
 import pubsub
 import copy
@@ -33,10 +34,12 @@ import copy
 NS_RSM = 'http://jabber.org/protocol/rsm'
 
 
-class RSMError(Exception):
+class RSMError(error.StanzaError):
     """
     RSM error.
     """
+    def __init__(self, text=None):
+        error.StanzaError.__init__(self, 'bad-request', text=text)
 
 
 class RSMNotFoundError(Exception):