diff --git a/packages/upload-client/test/helpers/car.js b/packages/upload-client/test/helpers/car.js
index b802cc889..51a8b15df 100644
--- a/packages/upload-client/test/helpers/car.js
+++ b/packages/upload-client/test/helpers/car.js
@@ -1,23 +1,26 @@
 import { CarWriter } from '@ipld/car'
 import * as CAR from '@ucanto/transport/car'
-import { toBlock } from './block.js'
+import { createFileEncoderStream } from '../../src/unixfs.js'
 
 /**
  * @param {Uint8Array} bytes
  */
 export async function toCAR(bytes) {
-  const block = await toBlock(bytes)
-  // @ts-expect-error old multiformats in @ipld/car
-  const { writer, out } = CarWriter.create(block.cid)
-  writer.put(block)
+  const readableStream = ((createFileEncoderStream(new Blob([bytes]), {})))
+
+  let blocks = [], chunks = []
+  // @ts-expect-error readable Stream is also an async iterable
+  for await (let block of readableStream) blocks.push(block)
+  const rootCID = blocks.at(-1)?.cid
+
+  const { writer, out } = CarWriter.create(rootCID)
+
+  for (const block of blocks) writer.put(block)
   writer.close()
 
-  const chunks = []
-  for await (const chunk of out) {
-    chunks.push(chunk)
-  }
+  for await (const chunk of out) chunks.push(chunk)
+  
   const blob = new Blob(chunks)
   const cid = await CAR.codec.link(new Uint8Array(await blob.arrayBuffer()))
-
-  return Object.assign(blob, { cid, roots: [block.cid] })
+  return  Object.assign(blob, { cid, roots: [rootCID] })
 }