diff --git a/atproto_firehose.py b/atproto_firehose.py
index ed0911c..3168a5f 100644
--- a/atproto_firehose.py
+++ b/atproto_firehose.py
@@ -6,13 +6,16 @@ import itertools
 import logging
 import os
 from queue import SimpleQueue
+from threading import Lock, Thread, Timer
 import time
 
 from carbox import read_car
 import dag_json
+from google.cloud import ndb
 from granary.bluesky import AT_URI_PATTERN
 from lexrpc.client import Client
 from oauth_dropins.webutil import util
+from oauth_dropins.webutil.appengine_config import ndb_client
 from oauth_dropins.webutil.appengine_info import DEBUG
 
 from atproto import ATProto, Cursor
@@ -36,24 +39,37 @@ new_commits = SimpleQueue()
 atproto_dids = None
 bridged_dids = None
 loaded_dids_at = None
+load_dids_lock = Lock()
+
 
 def load_dids():
+    # start in a a separate thread since it needs to make its own NDB context
+    # when it runs in the timer thread
+    thread = Thread(target=_load_dids)
+    thread.start()
+    thread.join()
+
+
+def _load_dids():
     global atproto_dids, bridged_dids, loaded_dids_at
 
-    if loaded_dids_at and loaded_dids_at > util.now() - RECONNECT_DELAY:
-        return
+    with load_dids_lock, ndb_client.context():
+        if loaded_dids_at and loaded_dids_at > util.now() - RECONNECT_DELAY:
+            return
 
-    atproto_query = ATProto.query(ATProto.enabled_protocols != None)
-    atproto_dids = frozenset(key.id() for key in atproto_query.iter(keys_only=True))
+        atproto_query = ATProto.query(ATProto.enabled_protocols != None)
+        atproto_dids = frozenset(key.id() for key in atproto_query.iter(keys_only=True))
 
-    others_queries = itertools.chain(*(
-        cls.query(cls.copies.protocol == 'atproto').iter()
-        for cls in set(models.PROTOCOLS.values())
-        if cls and cls != ATProto))
-    bridged_dids = frozenset(user.get_copy(ATProto) for user in others_queries)
+        others_queries = itertools.chain(*(
+            cls.query(cls.copies.protocol == 'atproto').iter()
+            for cls in set(models.PROTOCOLS.values())
+            if cls and cls != ATProto))
+        bridged_dids = frozenset(user.get_copy(ATProto) for user in others_queries)
 
-    logger.info(f'Loaded {len(atproto_dids)} ATProto, {len(bridged_dids)} bridged dids')
-    loaded_dids_at = util.now()
+        logger.info(f'Loaded {len(atproto_dids)} ATProto, {len(bridged_dids)} bridged dids')
+        loaded_dids_at = util.now()
+        if not DEBUG:
+            Timer(STORE_CURSOR_FREQ.total_seconds(), _load_dids).start()
 
 
 def subscribe(reconnect=True):