diff --git a/examples/onchain-signer/package.json b/examples/onchain-signer/package.json
index c2a53a4e..6a65a43b 100644
--- a/examples/onchain-signer/package.json
+++ b/examples/onchain-signer/package.json
@@ -25,6 +25,7 @@
     "@nomicfoundation/hardhat-verify": "^2.0.2",
     "@oasisprotocol/sapphire-contracts": "workspace:^",
     "@oasisprotocol/sapphire-hardhat": "workspace:^",
+    "@oasisprotocol/sapphire-paratime": "workspace:^",
     "@typechain/ethers-v6": "^0.5.1",
     "@typechain/hardhat": "^9.1.0",
     "@types/mocha": "^9.1.1",
diff --git a/examples/onchain-signer/test/CommentBox.ts b/examples/onchain-signer/test/CommentBox.ts
index d017283a..f464c1b2 100644
--- a/examples/onchain-signer/test/CommentBox.ts
+++ b/examples/onchain-signer/test/CommentBox.ts
@@ -1,9 +1,12 @@
 import { expect } from 'chai';
-import { Context } from 'mocha';
 import { ethers } from 'hardhat';
 import { parseEther, Wallet } from 'ethers';
 import { CommentBox, Gasless } from '../typechain-types';
 import { EthereumKeypairStruct } from '../typechain-types/contracts/Gasless';
+import {
+  isCalldataEnveloped,
+  wrapEthereumProvider
+} from "@oasisprotocol/sapphire-paratime";
 
 describe('CommentBox', function () {
   let commentBox: CommentBox;
@@ -34,8 +37,11 @@ describe('CommentBox', function () {
     console.log('    . gasless pubkey', wallet.address);
   });
 
-  async function commentGasless(comment: string, plain: boolean) {
-    const provider = ethers.provider;
+  // Request and send a gasless transaction. Set up sapphire-localnet image to
+  // run this test:
+  // docker run -it -p8544-8548:8544-8548 ghcr.io/oasisprotocol/sapphire-localnet
+  async function commentGasless(comment: string, plainProxy: boolean, unwrappedProvider: boolean) {
+    const provider = unwrappedProvider ? ethers.provider : wrapEthereumProvider(ethers.provider);
 
     const innercall = commentBox.interface.encodeFunctionData('comment', [
       comment,
@@ -43,7 +49,7 @@ describe('CommentBox', function () {
 
     const prevCommentCount = await commentBox.commentCount();
     let tx: string;
-    if (plain) {
+    if (plainProxy) {
       tx = await gasless.makeProxyTxPlain(
         await commentBox.getAddress(),
         innercall,
@@ -52,8 +58,8 @@ describe('CommentBox', function () {
       tx = await gasless.makeProxyTx(await commentBox.getAddress(), innercall);
     }
 
-    // TODO: https://github.com/oasisprotocol/sapphire-paratime/issues/179
     const response = await provider.broadcastTransaction(tx);
+    expect(isCalldataEnveloped(response.data)).eq(!plainProxy);
     await response.wait();
 
     const receipt = await provider.getTransactionReceipt(response.hash);
@@ -71,23 +77,39 @@ describe('CommentBox', function () {
     expect(await commentBox.commentCount()).eq(prevCommentCount + BigInt(1));
   });
 
-  it('Should comment gasless (encrypted)', async function () {
+  it('Should comment gasless (encrypted proxy tx, wrapped client)', async function () {
+    if ((await ethers.provider.getNetwork()).chainId == BigInt(1337)) {
+      this.skip();
+    }
+
+    await commentGasless('Hello, c10l world', false, false);
+  });
+
+  it('Should comment gasless (encrypted proxy tx, unwrapped client)', async function () {
+    if ((await ethers.provider.getNetwork()).chainId == BigInt(1337)) {
+      this.skip();
+    }
+
+    await commentGasless('Hello, c10l world', false, true);
+  });
+
+  it('Should comment gasless (plain proxy tx, wrapped client)', async function () {
     // Set up sapphire-localnet image to run this test:
     // docker run -it -p8544-8548:8544-8548 ghcr.io/oasisprotocol/sapphire-localnet
     if ((await ethers.provider.getNetwork()).chainId == BigInt(1337)) {
       this.skip();
     }
 
-    await commentGasless('Hello, c10l world', false);
+    await commentGasless('Hello, plain world', true, false);
   });
 
-  it('Should comment gasless (plain)', async function () {
+  it('Should comment gasless (plain proxy tx, unwrapped client)', async function () {
     // Set up sapphire-localnet image to run this test:
     // docker run -it -p8544-8548:8544-8548 ghcr.io/oasisprotocol/sapphire-localnet
     if ((await ethers.provider.getNetwork()).chainId == BigInt(1337)) {
       this.skip();
     }
 
-    await commentGasless('Hello, plain world', true);
+    await commentGasless('Hello, plain world', true, true);
   });
 });