diff --git a/backend/app/domains/products/cache_service.py b/backend/app/domains/products/cache_service.py
index 8eb2b81..dec6166 100644
--- a/backend/app/domains/products/cache_service.py
+++ b/backend/app/domains/products/cache_service.py
@@ -42,7 +42,7 @@ def store_stl_cache(step_hash: str, quality: str, stl_path: str) -> None:
     storage = get_storage()
     key = _cache_key(step_hash, quality)
     try:
-        storage.upload(stl_path, key)
+        storage.upload(Path(stl_path), key)
         logger.info("Stored STL cache: %s", key)
     except Exception as exc:
         logger.warning("Failed to store STL cache %s: %s", key, exc)