diff --git a/yarn-project/acir-simulator/package.json b/yarn-project/acir-simulator/package.json
index dab0530657fe..070ee6ba9521 100644
--- a/yarn-project/acir-simulator/package.json
+++ b/yarn-project/acir-simulator/package.json
@@ -36,7 +36,8 @@
     "@noir-lang/acvm_js": "0.26.1",
     "levelup": "^5.1.1",
     "memdown": "^6.1.1",
-    "tslib": "^2.4.0"
+    "tslib": "^2.4.0",
+    "viem": "^1.2.5"
   },
   "devDependencies": {
     "@aztec/merkle-tree": "workspace:^",
diff --git a/yarn-project/acir-simulator/src/client/private_execution.test.ts b/yarn-project/acir-simulator/src/client/private_execution.test.ts
index 5190c0ad9c1a..39268939906e 100644
--- a/yarn-project/acir-simulator/src/client/private_execution.test.ts
+++ b/yarn-project/acir-simulator/src/client/private_execution.test.ts
@@ -48,6 +48,7 @@ import { jest } from '@jest/globals';
 import { MockProxy, mock } from 'jest-mock-extended';
 import { default as levelup } from 'levelup';
 import { type MemDown, default as memdown } from 'memdown';
+import { getFunctionSelector } from 'viem';
 
 import { buildL1ToL2Message, getFunctionArtifact } from '../test/utils.js';
 import { computeSlotForMapping } from '../utils.js';
@@ -654,9 +655,8 @@ describe('Private Execution test suite', () => {
       const secretForL1ToL2MessageConsumption = new Fr(1n);
       const secretHashForRedeemingNotes = new Fr(2n);
       const canceller = EthAddress.random();
-      // Function selector: 0x25d46b0f keccak256('mint_private(uint256,bytes32,address)')
       const preimage = await buildL1ToL2Message(
-        '25d46b0f',
+        getFunctionSelector('mint_private(uint256,bytes32,address)').substring(2),
         [new Fr(bridgedAmount), secretHashForRedeemingNotes, canceller.toField()],
         contractAddress,
         secretForL1ToL2MessageConsumption,
diff --git a/yarn-project/acir-simulator/src/public/index.test.ts b/yarn-project/acir-simulator/src/public/index.test.ts
index f6480fe6f5d7..539b10c20f1d 100644
--- a/yarn-project/acir-simulator/src/public/index.test.ts
+++ b/yarn-project/acir-simulator/src/public/index.test.ts
@@ -23,6 +23,7 @@ import {
 
 import { MockProxy, mock } from 'jest-mock-extended';
 import { type MemDown, default as memdown } from 'memdown';
+import { getFunctionSelector } from 'viem';
 
 import { buildL1ToL2Message } from '../test/utils.js';
 import { computeSlotForMapping } from '../utils.js';
@@ -358,9 +359,8 @@ describe('ACIR public execution simulator', () => {
       const secret = new Fr(1n);
       const recipient = AztecAddress.random();
 
-      // Function selector: 0x63c9440d keccak256('mint_public(uint256,bytes32,address)')
       const preimage = await buildL1ToL2Message(
-        '63c9440d',
+        getFunctionSelector('mint_public(uint256,bytes32,address)').substring(2),
         [new Fr(bridgedAmount), recipient.toField(), canceller.toField()],
         contractAddress,
         secret,
diff --git a/yarn-project/yarn.lock b/yarn-project/yarn.lock
index 605dcd7c10a0..0415549e0855 100644
--- a/yarn-project/yarn.lock
+++ b/yarn-project/yarn.lock
@@ -82,6 +82,7 @@ __metadata:
     ts-node: ^10.9.1
     tslib: ^2.4.0
     typescript: ^5.0.4
+    viem: ^1.2.5
   languageName: unknown
   linkType: soft