diff --git a/synapse/util/__init__.py b/synapse/util/__init__.py
index 98a5a26ac5ae..2a2360ab5d67 100644
--- a/synapse/util/__init__.py
+++ b/synapse/util/__init__.py
@@ -26,7 +26,7 @@
 
 class DeferredTimedOutError(SynapseError):
     def __init__(self):
-        super(SynapseError, self).__init__(504, "Timed out")
+        super(DeferredTimedOutError, self).__init__(504, "Timed out")
 
 
 def unwrapFirstError(failure):