diff --git a/backend/app/main.py b/backend/app/main.py
index 23d7e98..7362ae3 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -42,21 +42,22 @@ async def ensure_mongo_index(collection, keys, **options) -> None:
     desired_unique = bool(options.get("unique"))
     desired_sparse = bool(options.get("sparse"))
 
-    async for index in collection.list_indexes():
-        if index["name"] == "_id_":
-            continue
-        index_key = list(index["key"].items())
-        same_key = index_key == key_list
-        same_name = index["name"] == name
-        if not same_key and not same_name:
-            continue
-        same_options = (
-            bool(index.get("unique")) == desired_unique
-            and bool(index.get("sparse")) == desired_sparse
-        )
-        if same_key and same_name and same_options:
-            return
-        await collection.drop_index(index["name"])
+    async with await collection.list_indexes() as cursor:
+        async for index in cursor:
+            if index["name"] == "_id_":
+                continue
+            index_key = list(index["key"].items())
+            same_key = index_key == key_list
+            same_name = index["name"] == name
+            if not same_key and not same_name:
+                continue
+            same_options = (
+                bool(index.get("unique")) == desired_unique
+                and bool(index.get("sparse")) == desired_sparse
+            )
+            if same_key and same_name and same_options:
+                return
+            await collection.drop_index(index["name"])
 
     await collection.create_index(keys, **options)