diff --git a/src/api/src/main.py b/src/api/src/main.py
index 83787fd..282f0da 100644
--- a/src/api/src/main.py
+++ b/src/api/src/main.py
@@ -193,7 +193,7 @@ async def handle_download(
             BytesIO(book_bytes),
             media_type=media_type,
             headers={
-                "Content-Disposition": f'attachment; filename="{slugify(metadata["title"])}_{story_id}{"_images" if download_images else ""}.{format}"'  # Thanks https://stackoverflow.com/a/72729058
+                "Content-Disposition": f'attachment; filename="{slugify(metadata["title"])}_{story_id}{"_images" if download_images else ""}.{format.value}"'  # Thanks https://stackoverflow.com/a/72729058
             },
         )