diff --git a/config.py b/config.py
index f6af26d..a31aeca 100644
--- a/config.py
+++ b/config.py
@@ -104,6 +104,7 @@ MEDIA_CACHE = MediaCache(GRIDFS, USER_AGENT)
 
 def create_indexes():
     DB.activities.create_index([("remote_id", pymongo.ASCENDING)])
+    DB.activities.create_index([("activity.object.id", pymongo.ASCENDING)])
 
     # Index for the block query
     DB.activities.create_index(