diff --git a/.changeset/a2a-response-reply-nonce.md b/.changeset/a2a-response-reply-nonce.md
new file mode 100644
index 00000000..8b171879
--- /dev/null
+++ b/.changeset/a2a-response-reply-nonce.md
@@ -0,0 +1,5 @@
+---
+"@agentcommercekit/ack-id": patch
+---
+
+Return the fresh reply nonce from A2A response handshakes.
diff --git a/packages/ack-id/src/a2a/sign-message.test.ts b/packages/ack-id/src/a2a/sign-message.test.ts
index fed6068d..15045c8d 100644
--- a/packages/ack-id/src/a2a/sign-message.test.ts
+++ b/packages/ack-id/src/a2a/sign-message.test.ts
@@ -3,6 +3,7 @@ import { createJwtSigner } from "@agentcommercekit/jwt"
 import { generateKeypair } from "@agentcommercekit/keys"
 import { beforeEach, describe, expect, it, vi } from "vitest"
 
+import { generateRandomNonce } from "./random"
 import {
   createA2AHandshakeMessage,
   createA2AHandshakeMessageFromJwt,
@@ -138,6 +139,22 @@ describe("createA2AHandshakeMessage", () => {
     expect(result.message.role).toBe("agent")
   })
 
+  it("returns the fresh reply nonce when responding to a handshake", async () => {
+    vi.mocked(generateRandomNonce).mockReturnValueOnce("fresh-reply-nonce")
+
+    const result = await createA2AHandshakeMessage(
+      "agent",
+      {
+        recipient: userDid,
+        vc: testCredential,
+        requestNonce: "initiator-nonce",
+      },
+      { did: agentDid, jwtSigner },
+    )
+
+    expect(result.nonce).toBe("fresh-reply-nonce")
+  })
+
   it("returns the signed JWT in the message data part", async () => {
     const result = await createA2AHandshakeMessage(
       "agent",
diff --git a/packages/ack-id/src/a2a/sign-message.ts b/packages/ack-id/src/a2a/sign-message.ts
index a4a041bc..f3e26ba4 100644
--- a/packages/ack-id/src/a2a/sign-message.ts
+++ b/packages/ack-id/src/a2a/sign-message.ts
@@ -122,7 +122,7 @@ export async function createA2AHandshakeMessage(
   return {
     sig: jwt,
     jti,
-    nonce: payload.nonce,
+    nonce: payload.replyNonce ?? payload.nonce,
     message,
   }
 }