diff --git a/packages/api/src/utils/w3up.js b/packages/api/src/utils/w3up.js
index 0dd0d10b72..003460955d 100644
--- a/packages/api/src/utils/w3up.js
+++ b/packages/api/src/utils/w3up.js
@@ -4,8 +4,9 @@ import { StoreMemory } from '@web3-storage/access/stores/store-memory'
 import { CID } from 'multiformats/cid'
 import { base64 } from 'multiformats/bases/base64'
 import { identity } from 'multiformats/hashes/identity'
-import { CarReader } from '@ipld/car'
+import { CarReader, CarWriter } from '@ipld/car'
 import { importDAG } from '@ucanto/core/delegation'
+import * as ucanto from '@ucanto/core'
 
 /**
  * @param {object} env
@@ -70,3 +71,33 @@ export async function readProofFromBytes(bytes) {
     throw err
   }
 }
+
+/**
+ * @param {import('@ucanto/interface').Delegation} delegation - delegation to encode
+ */
+export async function encodeDelegationAsCid(delegation) {
+  const { writer, out } = CarWriter.create()
+  /** @type {Array<Uint8Array>} */
+  const carChunks = []
+  await Promise.all([
+    // write delegation blocks
+    (async () => {
+      for (const block of delegation.export()) {
+        // @ts-expect-error different Block types
+        await writer.put(block)
+      }
+      await writer.close()
+    })(),
+    // read out
+    (async () => {
+      for await (const chunk of out) {
+        carChunks.push(chunk)
+      }
+    })(),
+  ])
+  // now get car chunks
+  const car = new Blob(carChunks)
+  const bytes = new Uint8Array(await car.arrayBuffer())
+  const cid = CID.createV1(ucanto.CAR.code, identity.digest(bytes))
+  return cid
+}
diff --git a/packages/api/test/nfts-upload.spec.js b/packages/api/test/nfts-upload.spec.js
index e2a4caad54..c1ef8de7c0 100644
--- a/packages/api/test/nfts-upload.spec.js
+++ b/packages/api/test/nfts-upload.spec.js
@@ -27,9 +27,14 @@ import path from 'node:path'
 import { FormData } from 'undici'
 import { createCarCid } from '../src/utils/car.js'
 import { createServer } from 'node:http'
+import { ed25519 } from '@ucanto/principal'
+import { delegate } from '@ucanto/core'
+import { encodeDelegationAsCid } from '../src/utils/w3up.js'
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url))
 
+const nftStorageSpace = ed25519.generate()
+const nftStorageApiPrincipal = ed25519.generate()
 const mockW3up = createListeningMockW3up()
 
 test.before(async (t) => {
@@ -38,9 +43,20 @@ test.before(async (t) => {
     overrides: {
       LINKDEX_URL: linkdexUrl,
       W3UP_URL: (await mockW3up).url.toString(),
-      W3_NFTSTORAGE_SPACE: `did:key:zTodo`,
-      W3_NFTSTORAGE_PRINCIPAL: 'zTodo',
-      W3_NFTSTORAGE_PROOF: 'zTodo',
+      W3_NFTSTORAGE_SPACE: (await nftStorageSpace).did(),
+      W3_NFTSTORAGE_PRINCIPAL: (await nftStorageApiPrincipal).did(),
+      W3_NFTSTORAGE_PROOF: (
+        await encodeDelegationAsCid(
+          await delegate({
+            issuer: await nftStorageSpace,
+            audience: await nftStorageApiPrincipal,
+            capabilities: [
+              { can: 'store/add', with: (await nftStorageSpace).did() },
+              { can: 'upload/add', with: (await nftStorageSpace).did() },
+            ],
+          })
+        )
+      ).toString(),
     },
   })
 })