diff --git a/backend/app/api/v1/assets.py b/backend/app/api/v1/assets.py
index 58d6efe..d1fe66f 100644
--- a/backend/app/api/v1/assets.py
+++ b/backend/app/api/v1/assets.py
@@ -274,7 +274,7 @@ async def upload_asset(
     asset = Asset(
         id=asset_id,
         user_id=user.id if user else None,
-        project_id=UUID(project_id) if project_id else None,
+        project_id=UUID(project_id) if (project_id and isinstance(project_id, str)) else None,
         original_filename=file.filename,
         stored_filename=stored_filename,
         file_path=file_path,