diff --git a/src/db/multipart.ts b/src/db/multipart.ts
index 188b15d..ab5815a 100644
--- a/src/db/multipart.ts
+++ b/src/db/multipart.ts
@@ -85,7 +85,7 @@ export const listMultipartParts = async (uploadId: string): Promise<MultipartPar
     telegramFileId: r.telegram_file_id as string,
     telegramFileUniqueId: r.telegram_file_unique_id as string,
     storageMessageId: r.storage_message_id as number,
-    sizeBytes: r.size_bytes as number,
+    sizeBytes: Number(r.size_bytes),
     etag: r.etag as string,
     createdAt: new Date(r.created_at as string),
   }));
diff --git a/src/routes/s3.ts b/src/routes/s3.ts
index 5fb6d41..b286407 100644
--- a/src/routes/s3.ts
+++ b/src/routes/s3.ts
@@ -393,7 +393,7 @@ const handleGetMultipartObject = async (
     );
   }
 
-  const totalSize = parts.reduce((sum, p) => sum + p.sizeBytes, 0);
+  const totalSize = parts.reduce((sum, p) => sum + Number(p.sizeBytes), 0);
   const range = parseRangeHeader(headers.range || null, totalSize);
   if (range.type === 'invalid') {
     return s3ErrorResponse(