diff --git a/backend/app/storage.py b/backend/app/storage.py
index 7be4d29e..2ea37c3a 100644
--- a/backend/app/storage.py
+++ b/backend/app/storage.py
@@ -4,6 +4,7 @@
 import orjson
 from langchain.schema.messages import messages_from_dict
 from langchain.utilities.redis import get_client
+from redis.client import Redis as RedisType
 
 
 def assistants_list_key(user_id: str):
@@ -33,7 +34,7 @@ def thread_messages_key(user_id: str, thread_id: str):
 public_user_id = "eef39817-c173-4eb6-8be4-f77cf37054fb"
 
 
-def dump(map: dict) -> dict:
+def _dump(map: dict) -> dict:
     return {k: orjson.dumps(v) if v is not None else None for k, v in map.items()}
 
 
@@ -41,8 +42,16 @@ def load(keys: list[str], values: list[bytes]) -> dict:
     return {k: orjson.loads(v) if v is not None else None for k, v in zip(keys, values)}
 
 
+def _get_redis_client() -> RedisType:
+    """Get a Redis client."""
+    url = os.environ.get("REDIS_URL")
+    if not url:
+        raise ValueError("REDIS_URL not set")
+    return get_client(url)
+
+
 def list_assistants(user_id: str):
-    client = get_client(os.environ.get("REDIS_URL"))
+    client = _get_redis_client()
     ids = [orjson.loads(id) for id in client.smembers(assistants_list_key(user_id))]
     with client.pipeline() as pipe:
         for id in ids:
@@ -54,7 +63,7 @@ def list_assistants(user_id: str):
 def list_public_assistants(assistant_ids: list[str]):
     if not assistant_ids:
         return []
-    client = get_client(os.environ.get("REDIS_URL"))
+    client = _get_redis_client()
     ids = [
         id
         for id, is_public in zip(
@@ -84,19 +93,19 @@ def put_assistant(
         "updated_at": datetime.utcnow(),
         "public": public,
     }
-    client = get_client(os.environ.get("REDIS_URL"))
+    client = _get_redis_client()
     with client.pipeline() as pipe:
         pipe.sadd(assistants_list_key(user_id), orjson.dumps(assistant_id))
-        pipe.hset(assistant_key(user_id, assistant_id), mapping=dump(saved))
+        pipe.hset(assistant_key(user_id, assistant_id), mapping=_dump(saved))
         if public:
             pipe.sadd(assistants_list_key(public_user_id), orjson.dumps(assistant_id))
-            pipe.hset(assistant_key(public_user_id, assistant_id), mapping=dump(saved))
+            pipe.hset(assistant_key(public_user_id, assistant_id), mapping=_dump(saved))
         pipe.execute()
     return saved
 
 
 def list_threads(user_id: str):
-    client = get_client(os.environ.get("REDIS_URL"))
+    client = _get_redis_client()
     ids = [orjson.loads(id) for id in client.smembers(threads_list_key(user_id))]
     with client.pipeline() as pipe:
         for id in ids:
@@ -106,7 +115,7 @@ def list_threads(user_id: str):
 
 
 def get_thread_messages(user_id: str, thread_id: str):
-    client = get_client(os.environ.get("REDIS_URL"))
+    client = _get_redis_client()
     messages = client.lrange(thread_messages_key(user_id, thread_id), 0, -1)
     return {
         "messages": [
@@ -124,10 +133,10 @@ def put_thread(user_id: str, thread_id: str, *, assistant_id: str, name: str):
         "name": name,
         "updated_at": datetime.utcnow(),
     }
-    client = get_client(os.environ.get("REDIS_URL"))
+    client = _get_redis_client()
     with client.pipeline() as pipe:
         pipe.sadd(threads_list_key(user_id), orjson.dumps(thread_id))
-        pipe.hset(thread_key(user_id, thread_id), mapping=dump(saved))
+        pipe.hset(thread_key(user_id, thread_id), mapping=_dump(saved))
         pipe.execute()
     return saved