1 files changed, 1 insertions, 1 deletions
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 9b09c08b89..c2d72a82cf 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -192,7 +192,7 @@ class Cache(object):
         callbacks = [callback] if callback else []
         self.check_thread()
         observable = ObservableDeferred(value, consumeErrors=True)
-        observer = defer.maybeDeferred(observable.observe)
+        observer = observable.observe()
         entry = CacheEntry(deferred=observable, callbacks=callbacks)
 
         existing_entry = self._pending_deferred_cache.pop(key, None)