diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index 55ba1c08c0..e863a8f8a9 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -81,6 +81,7 @@ class ExpiringCache(object):
             cache_counter.inc_hits(self._cache_name)
         except KeyError:
             cache_counter.inc_misses(self._cache_name)
+            raise
 
         if self._reset_expiry_on_get:
             entry.time = self._clock.time_msec()