diff --git a/src/pages/sign/index.tsx b/src/pages/sign/index.tsx
index 63e71dd..0fbeaf5 100644
--- a/src/pages/sign/index.tsx
+++ b/src/pages/sign/index.tsx
@@ -54,6 +54,7 @@ import {
   SigitFile
 } from '../../utils/file.ts'
 import { ARRAY_BUFFER, DEFLATE } from '../../utils/const.ts'
+import { generateTimestamp } from '../../utils/opentimestamps.ts'
 enum SignedStatus {
   Fully_Signed,
   User_Is_Next_Signer,
@@ -549,6 +550,12 @@ export const SignPage = () => {
 
     const updatedMeta = updateMetaSignatures(meta, signedEvent)
 
+    const timestamp = await generateTimestamp(signedEvent.id)
+    if (timestamp) {
+      updatedMeta.timestamps = [...(updatedMeta.timestamps || []), timestamp]
+      updatedMeta.modifiedAt = unixNow()
+    }
+
     if (await isOnline()) {
       await handleOnlineFlow(updatedMeta)
     } else {
diff --git a/src/utils/opentimestamps.ts b/src/utils/opentimestamps.ts
index 3d6bb78..4cbc036 100644
--- a/src/utils/opentimestamps.ts
+++ b/src/utils/opentimestamps.ts
@@ -1,6 +1,7 @@
 import { Timestamp } from '../types'
 import { retry } from './retry.ts'
-import { bytesToHex, hexToBytes } from '@noble/hashes/utils'
+import { bytesToHex } from '@noble/hashes/utils'
+import { utf8Encoder } from 'nostr-tools/utils'
 
 /**
  * Generates a timestamp for the provided nostr event ID.
@@ -20,18 +21,16 @@ export const generateTimestamp = async (
   }
 }
 
-const timestamp = async (hash: string): Promise<string> => {
+const timestamp = async (nostrId: string): Promise<string> => {
   const detachedTimestamp =
-    window.OpenTimestamps.DetachedTimestampFile.fromHash(
+    window.OpenTimestamps.DetachedTimestampFile.fromBytes(
       new window.OpenTimestamps.Ops.OpSHA256(),
-      hexToBytes(hash)
+      utf8Encoder.encode(nostrId)
     )
 
   await window.OpenTimestamps.stamp(detachedTimestamp)
   const ctx = new window.OpenTimestamps.Context.StreamSerialization()
   detachedTimestamp.serialize(ctx)
   const timestampBytes = ctx.getOutput()
-  const hex = bytesToHex(timestampBytes)
-
-  return hex
+  return bytesToHex(timestampBytes)
 }