diff --git a/zerver/lib/cache_helpers.py b/zerver/lib/cache_helpers.py
index 53f70eecb9..baa4593fb6 100644
--- a/zerver/lib/cache_helpers.py
+++ b/zerver/lib/cache_helpers.py
@@ -1,5 +1,5 @@
 from __future__ import absolute_import
-from typing import Any
+from typing import Any, Dict, Callable, Tuple
 
 # This file needs to be different from cache.py because cache.py
 # cannot import anything from zerver.models or we'd have an import
@@ -19,13 +19,16 @@ from django.db.models import Q
 MESSAGE_CACHE_SIZE = 75000
 
 def cache_save_message(message):
+    # type: (Message) -> None
     cache_set(message_cache_key(message.id), message, timeout=3600*24)
 
 @cache_with_key(message_cache_key, timeout=3600*24)
 def cache_get_message(message_id):
+    # type: (int) -> Message
     return Message.objects.select_related().get(id=message_id)
 
 def message_fetch_objects():
+    # type: () -> List[Any]
     try:
         max_id = Message.objects.only('id').order_by("-id")[0].id
     except IndexError:
@@ -34,26 +37,33 @@ def message_fetch_objects():
                                                     id__gt=max_id - MESSAGE_CACHE_SIZE)
 
 def message_cache_items(items_for_remote_cache, message):
+    # type: (Dict[str, Tuple[Message]], Message) -> None
     items_for_remote_cache[message_cache_key(message.id)] = (message,)
 
 def user_cache_items(items_for_remote_cache, user_profile):
+    # type: (Dict[str, Tuple[UserProfile]], UserProfile) -> None
     items_for_remote_cache[user_profile_by_email_cache_key(user_profile.email)] = (user_profile,)
     items_for_remote_cache[user_profile_by_id_cache_key(user_profile.id)] = (user_profile,)
 
 def stream_cache_items(items_for_remote_cache, stream):
+    # type: (Dict[str, Tuple[Stream]], Stream) -> None
     items_for_remote_cache[get_stream_cache_key(stream.name, stream.realm_id)] = (stream,)
 
 def client_cache_items(items_for_remote_cache, client):
+    # type: (Dict[str, Tuple[Client]], Client) -> None
     items_for_remote_cache[get_client_cache_key(client.name)] = (client,)
 
 def huddle_cache_items(items_for_remote_cache, huddle):
+    # type: (Dict[str, Tuple[Huddle]], Huddle) -> None
     items_for_remote_cache[huddle_hash_cache_key(huddle.huddle_hash)] = (huddle,)
 
 def recipient_cache_items(items_for_remote_cache, recipient):
+    # type: (Dict[str, Tuple[Recipient]], Recipient) -> None
     items_for_remote_cache[get_recipient_cache_key(recipient.type, recipient.type_id)] = (recipient,)
 
 session_engine = import_module(settings.SESSION_ENGINE)
 def session_cache_items(items_for_remote_cache, session):
+    # type: (Dict[str, str], Session) -> None
     store = session_engine.SessionStore(session_key=session.session_key)
     items_for_remote_cache[store.cache_key] = store.decode(session.session_data)
 
@@ -71,9 +81,10 @@ cache_fillers = {
     'message': (message_fetch_objects, message_cache_items, 3600 * 24, 1000),
     'huddle': (lambda: Huddle.objects.select_related().all(), huddle_cache_items, 3600*24*7, 10000),
     'session': (lambda: Session.objects.all(), session_cache_items, 3600*24*7, 10000),
-    }
+    } # type: Dict[str, Tuple[Callable[[], List[Any]], Callable[[Dict[str, Any], Any], None], int, int]]
 
 def fill_remote_cache(cache):
+    # type: (str) -> None
     remote_cache_time_start = get_remote_cache_time()
     remote_cache_requests_start = get_remote_cache_requests()
     items_for_remote_cache = {} # type: Dict[str, Any]