diff --git a/changelog.d/3447.misc b/changelog.d/3447.misc
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py
index 817118e30f51..0fb862000128 100644
--- a/synapse/util/caches/stream_change_cache.py
+++ b/synapse/util/caches/stream_change_cache.py
@@ -78,7 +78,8 @@ def get_entities_changed(self, entities, stream_pos):
             not_known_entities = set(entities) - set(self._entity_to_key)
 
             result = (
-                set(self._cache.values()[self._cache.bisect_right(stream_pos) :])
+                {self._cache[k] for k in self._cache.islice(
+                    start=self._cache.bisect_right(stream_pos))}
                 .intersection(entities)
                 .union(not_known_entities)
             )
@@ -113,7 +114,8 @@ def get_all_entities_changed(self, stream_pos):
         assert type(stream_pos) is int
 
         if stream_pos >= self._earliest_known_stream_pos:
-            return self._cache.values()[self._cache.bisect_right(stream_pos) :]
+            return [self._cache[k] for k in self._cache.islice(
+                start=self._cache.bisect_right(stream_pos))]
         else:
             return None