diff --git a/IntegrationTests/TestSuites/Sources/PrimaryTests/main.swift b/IntegrationTests/TestSuites/Sources/PrimaryTests/main.swift
index a9d12710..71615103 100644
--- a/IntegrationTests/TestSuites/Sources/PrimaryTests/main.swift
+++ b/IntegrationTests/TestSuites/Sources/PrimaryTests/main.swift
@@ -400,7 +400,7 @@ try test("Call Function With This") {
     let setName = try expectFunction(getJSValue(this: cat1, name: "setName"))
 
     // Direct call without this
-    try expectEqual(getIsCat(), .undefined)
+    _ = try expectThrow(try getIsCat.throws())
 
     // Call with this
     let gotIsCat = getIsCat(this: cat1)
diff --git a/IntegrationTests/bin/benchmark-tests.js b/IntegrationTests/bin/benchmark-tests.js
index 424ce819..0d8b5410 100644
--- a/IntegrationTests/bin/benchmark-tests.js
+++ b/IntegrationTests/bin/benchmark-tests.js
@@ -1,5 +1,5 @@
-const { startWasiTask } = require("../lib");
-const { performance } = require("perf_hooks");
+import { startWasiTask } from "../lib.js";
+import { performance } from "perf_hooks";
 
 const SAMPLE_ITERATION = 1000000
 
diff --git a/IntegrationTests/bin/concurrency-tests.js b/IntegrationTests/bin/concurrency-tests.js
index 47ef4abd..02489c95 100644
--- a/IntegrationTests/bin/concurrency-tests.js
+++ b/IntegrationTests/bin/concurrency-tests.js
@@ -1,4 +1,4 @@
-const { startWasiTask } = require("../lib");
+import { startWasiTask } from "../lib.js";
 
 Error.stackTraceLimit = Infinity;
 
diff --git a/IntegrationTests/bin/primary-tests.js b/IntegrationTests/bin/primary-tests.js
index 50532cea..36ac6581 100644
--- a/IntegrationTests/bin/primary-tests.js
+++ b/IntegrationTests/bin/primary-tests.js
@@ -102,7 +102,7 @@ global.objectDecodingTest = {
     bi: BigInt(3)
 };
 
-const { startWasiTask, WASI } = require("../lib");
+import { startWasiTask } from "../lib.js";
 
 startWasiTask("./dist/PrimaryTests.wasm").catch((err) => {
     console.log(err);
diff --git a/IntegrationTests/lib.js b/IntegrationTests/lib.js
index 71570bfe..2ed9a918 100644
--- a/IntegrationTests/lib.js
+++ b/IntegrationTests/lib.js
@@ -1,10 +1,7 @@
-const SwiftRuntime = require("javascript-kit-swift").SwiftRuntime;
-const NodeWASI = require("wasi").WASI;
-const { WASI: MicroWASI, useAll } = require("uwasi");
-
-const promisify = require("util").promisify;
-const fs = require("fs");
-const readFile = promisify(fs.readFile);
+import { SwiftRuntime } from "javascript-kit-swift"
+import { WASI as NodeWASI } from "wasi"
+import { WASI as MicroWASI, useAll } from "uwasi"
+import * as fs from "fs/promises"
 
 const WASI = {
     MicroWASI: ({ programName }) => {
@@ -54,10 +51,10 @@ const selectWASIBackend = () => {
     return WASI.Node;
 };
 
-const startWasiTask = async (wasmPath, wasiConstructor = selectWASIBackend()) => {
+export const startWasiTask = async (wasmPath, wasiConstructor = selectWASIBackend()) => {
     const swift = new SwiftRuntime();
     // Fetch our Wasm File
-    const wasmBinary = await readFile(wasmPath);
+    const wasmBinary = await fs.readFile(wasmPath);
     const wasi = wasiConstructor({ programName: wasmPath });
 
     // Instantiate the WebAssembly file
@@ -74,5 +71,3 @@ const startWasiTask = async (wasmPath, wasiConstructor = selectWASIBackend()) =>
     // Start the WebAssembly WASI instance!
     wasi.start(instance, swift);
 };
-
-module.exports = { startWasiTask, WASI };
diff --git a/IntegrationTests/package.json b/IntegrationTests/package.json
index 29a3597c..8491e91f 100644
--- a/IntegrationTests/package.json
+++ b/IntegrationTests/package.json
@@ -1,5 +1,6 @@
 {
   "private": true,
+  "type": "module",
   "dependencies": {
     "uwasi": "^1.2.0",
     "javascript-kit-swift": "file:.."
diff --git a/Makefile b/Makefile
index 35530b26..e71734a5 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ test:
 unittest:
 	@echo Running unit tests
 	swift build --build-tests --triple wasm32-unknown-wasi -Xswiftc -Xclang-linker -Xswiftc -mexec-model=reactor -Xlinker --export-if-defined=main -Xlinker --export-if-defined=__main_argc_argv --static-swift-stdlib -Xswiftc -static-stdlib
-	node --experimental-wasi-unstable-preview1 scripts/test-harness.js ./.build/wasm32-unknown-wasi/debug/JavaScriptKitPackageTests.wasm
+	node --experimental-wasi-unstable-preview1 scripts/test-harness.mjs ./.build/wasm32-unknown-wasi/debug/JavaScriptKitPackageTests.wasm
 
 .PHONY: benchmark_setup
 benchmark_setup:
diff --git a/scripts/test-harness.js b/scripts/test-harness.mjs
similarity index 84%
rename from scripts/test-harness.js
rename to scripts/test-harness.mjs
index 27f9e93a..b0384d4d 100644
--- a/scripts/test-harness.js
+++ b/scripts/test-harness.mjs
@@ -1,6 +1,6 @@
 Error.stackTraceLimit = Infinity;
 
-const { startWasiTask } = require("../IntegrationTests/lib");
+import { startWasiTask } from "../IntegrationTests/lib.js";
 
 if (process.env["JAVASCRIPTKIT_WASI_BACKEND"] === "MicroWASI") {
   console.log("Skipping XCTest tests for MicroWASI because it is not supported yet.");