diff --git a/backend/tests/test_classifier.py b/backend/tests/test_classifier.py
index 33e555a..06c7a87 100644
--- a/backend/tests/test_classifier.py
+++ b/backend/tests/test_classifier.py
@@ -184,6 +184,7 @@ async def test_celery_task_uses_user_provider(db_session):
     mock_doc.content_type = "text/plain"
     mock_doc.extracted_text = ""
     mock_doc.status = "uploaded"
+    mock_doc.storage_backend = "minio"
 
     mock_user = MagicMock()
     mock_user.ai_provider = "anthropic"