diff --git a/app/main.py b/app/main.py
index dbbd53d..ab73c99 100644
--- a/app/main.py
+++ b/app/main.py
@@ -94,12 +94,12 @@ async def register(user: UserRegisterDTO):
         )
 
     hashed_password = get_password_hash(user.password)
-    users_collection.insert_one({"username": user.username, "password": hashed_password})
+    user_id = users_collection.insert_one({"username": user.username, "password": hashed_password})
 
     access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
     access_token = create_access_token(data={"sub": user.username}, expires_delta=access_token_expires)
 
-    return {"access_token": access_token, "token_type": "bearer", "user_id": str(user["_id"])}
+    return {"access_token": access_token, "token_type": "bearer", "user_id": str(user_id)}
 
 @app.post(
     path="/login",