diff --git a/docs/tcp_replication.rst b/docs/tcp_replication.rst
index 852f1113a3..73436cea62 100644
--- a/docs/tcp_replication.rst
+++ b/docs/tcp_replication.rst
@@ -240,3 +240,8 @@ However, there are times when a number of caches need to be invalidated at the
 same time with the same key. To reduce traffic we batch those invalidations into
 a single poke by defining a special cache name that workers understand to mean
 to expand to invalidate the correct caches.
+
+Currently the special cache names are declared in ``synapse/storage/_base.py``
+and are:
+
+1. ``cs_cache_fake`` ─ invalidates caches that depend on the current state
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 9db594bc42..f1a5366b95 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -1201,7 +1201,7 @@ class SQLBaseStore(object):
         Args:
             txn
             room_id (str): Room where state changed
-            members_changed (Iterable[str]): The user_ids of members that have changed
+            members_changed (iterable[str]): The user_ids of members that have changed
         """
         txn.call_after(self._invalidate_state_caches, room_id, members_changed)
 
@@ -1216,7 +1216,8 @@ class SQLBaseStore(object):
 
         Args:
             room_id (str): Room where state changed
-            members_changed (set[str]): The user_ids of members that have changed
+            members_changed (iterable[str]): The user_ids of members that have
+                changed
         """
         for member in members_changed:
             self.get_rooms_for_user_with_stream_ordering.invalidate((member,))