diff --git a/server/src/services/documentParser.ts b/server/src/services/documentParser.ts
index a37a704..175e361 100644
--- a/server/src/services/documentParser.ts
+++ b/server/src/services/documentParser.ts
@@ -252,9 +252,10 @@ async function convertViaSandbox(buffer: Buffer, extension: string): Promise<Buf
   const timeout = setTimeout(() => controller.abort(), PROCESSING_TIMEOUT_MS);
 
   try {
+    const body = new Uint8Array(buffer);
     const response = await fetch(`${SANDBOX_URL}/convert?ext=${extension}`, {
       method: 'POST',
-      body: buffer,
+      body,
       signal: controller.signal,
       headers: { 'Content-Type': 'application/octet-stream' },
     });