diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index ba2410998a96..26025504393e 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -18,6 +18,7 @@
 import logging
 from typing import (
     Any,
+    Awaitable,
     Callable,
     Dict,
     Generic,
@@ -354,7 +355,7 @@ class DeferredCacheListDescriptor(_CacheDescriptorBase):
 
     def __init__(
         self,
-        orig: Callable[..., Any],
+        orig: Callable[..., Awaitable[Dict]],
         cached_method_name: str,
         list_name: str,
         num_args: Optional[int] = None,
@@ -385,13 +386,13 @@ def __init__(
 
     def __get__(
         self, obj: Optional[Any], objtype: Optional[Type] = None
-    ) -> Callable[..., Any]:
+    ) -> Callable[..., defer.Deferred[Dict[Hashable, Any]]]:
         cached_method = getattr(obj, self.cached_method_name)
         cache: DeferredCache[CacheKey, Any] = cached_method.cache
         num_args = cached_method.num_args
 
         @functools.wraps(self.orig)
-        def wrapped(*args: Any, **kwargs: Any) -> Any:
+        def wrapped(*args: Any, **kwargs: Any) -> defer.Deferred[Dict]:
             # If we're passed a cache_context then we'll want to call its
             # invalidate() whenever we are invalidated
             invalidate_callback = kwargs.pop("on_invalidate", None)