diff --git a/src/strip-loader.ts b/src/strip-loader.ts
index 61b9e6700..e76be2605 100644
--- a/src/strip-loader.ts
+++ b/src/strip-loader.ts
@@ -13,12 +13,10 @@ export async function load(
 ) {
 	const { format } = context;
 	if (format?.endsWith("-typescript")) {
-		// Use format 'module' so it returns the source as-is, without stripping the types.
-		// Format 'commonjs' would not return the source for historical reasons.
 		try {
 			const { source } = await nextLoad(url, {
 				...context,
-				format: "module",
+				format,
 			});
 			// biome-ignore lint/style/noNonNullAssertion: If module exists, it will have a source
 			const { code } = transformSync(source!.toString(), {
diff --git a/src/transform-loader.ts b/src/transform-loader.ts
index 8e859b4c4..ff9fa9231 100644
--- a/src/transform-loader.ts
+++ b/src/transform-loader.ts
@@ -15,11 +15,9 @@ export async function load(
 	const { format } = context;
 	if (format?.endsWith("-typescript")) {
 		try {
-			// Use format 'module' so it returns the source as-is, without stripping the types.
-			// Format 'commonjs' would not return the source for historical reasons.
 			const { source } = await nextLoad(url, {
 				...context,
-				format: "module",
+				format,
 			});
 
 			// biome-ignore lint/style/noNonNullAssertion: If module exists, it will have a source
diff --git a/test/fixtures/commonjs.cts b/test/fixtures/commonjs.cts
new file mode 100644
index 000000000..d29bb2812
--- /dev/null
+++ b/test/fixtures/commonjs.cts
@@ -0,0 +1,9 @@
+const message: string = "Hello from CommonJS TypeScript (.cts)!";
+
+function greet(name: string): void {
+    console.log(`${message} - ${name}`);
+}
+
+module.exports = { greet };
+
+greet("Test");
diff --git a/test/fixtures/commonjs.ts b/test/fixtures/commonjs.ts
new file mode 100644
index 000000000..309b94e9c
--- /dev/null
+++ b/test/fixtures/commonjs.ts
@@ -0,0 +1,9 @@
+const message: string = "Hello from CommonJS TypeScript!";
+
+function greet(name: string): void {
+    console.log(`${message} - ${name}`);
+}
+
+module.exports = { greet };
+
+greet("Test");
diff --git a/test/fixtures/esm.mts b/test/fixtures/esm.mts
new file mode 100644
index 000000000..8c951aa91
--- /dev/null
+++ b/test/fixtures/esm.mts
@@ -0,0 +1,7 @@
+const message: string = "Hello from ESM TypeScript!";
+
+export function greet(name: string): void {
+    console.log(`${message} - ${name}`);
+}
+
+greet("Test");
diff --git a/test/fixtures/esm/esm.ts b/test/fixtures/esm/esm.ts
new file mode 100644
index 000000000..8c951aa91
--- /dev/null
+++ b/test/fixtures/esm/esm.ts
@@ -0,0 +1,7 @@
+const message: string = "Hello from ESM TypeScript!";
+
+export function greet(name: string): void {
+    console.log(`${message} - ${name}`);
+}
+
+greet("Test");
diff --git a/test/fixtures/esm/package.json b/test/fixtures/esm/package.json
new file mode 100644
index 000000000..9e26dfeeb
--- /dev/null
+++ b/test/fixtures/esm/package.json
@@ -0,0 +1 @@
+{}
\ No newline at end of file
diff --git a/test/loader.test.js b/test/loader.test.js
index 3d00a86db..b0257792f 100644
--- a/test/loader.test.js
+++ b/test/loader.test.js
@@ -99,3 +99,99 @@ test("should throw syntax error for invalid typescript", async (t) => {
 	match(result.stderr, /await isn't allowed in non-async function/);
 	strictEqual(result.code, 1);
 });
+
+test("should work with commonjs typescript files using strip", async () => {
+	const result = await spawnPromisified(process.execPath, [
+		"--no-warnings",
+		"--import=./dist/register-strip.mjs",
+		fixturesPath("commonjs.ts"),
+	]);
+
+	strictEqual(result.stderr, "");
+	match(result.stdout, /Hello from CommonJS TypeScript!/);
+	strictEqual(result.code, 0);
+});
+
+test("should work with commonjs typescript files using transform", async () => {
+	const result = await spawnPromisified(process.execPath, [
+		"--no-warnings",
+		"--import=./dist/register-transform.mjs",
+		fixturesPath("commonjs.ts"),
+	]);
+
+	strictEqual(result.stderr, "");
+	match(result.stdout, /Hello from CommonJS TypeScript!/);
+	strictEqual(result.code, 0);
+});
+
+test("should work with .cts files using strip", async () => {
+	const result = await spawnPromisified(process.execPath, [
+		"--no-warnings",
+		"--import=./dist/register-strip.mjs",
+		fixturesPath("commonjs.cts"),
+	]);
+
+	strictEqual(result.stderr, "");
+	match(result.stdout, /Hello from CommonJS TypeScript \(\.cts\)!/);
+	strictEqual(result.code, 0);
+});
+
+test("should work with .cts files using transform", async () => {
+	const result = await spawnPromisified(process.execPath, [
+		"--no-warnings",
+		"--import=./dist/register-transform.mjs",
+		fixturesPath("commonjs.cts"),
+	]);
+
+	strictEqual(result.stderr, "");
+	match(result.stdout, /Hello from CommonJS TypeScript \(\.cts\)!/);
+	strictEqual(result.code, 0);
+});
+
+test("should work with esm typescript files using strip", async () => {
+	const result = await spawnPromisified(process.execPath, [
+		"--no-warnings",
+		"--import=./dist/register-strip.mjs",
+		fixturesPath("esm/esm.ts"),
+	]);
+
+	strictEqual(result.stderr, "");
+	match(result.stdout, /Hello from ESM TypeScript!/);
+	strictEqual(result.code, 0);
+});
+
+test("should work with esm typescript files using transform", async () => {
+	const result = await spawnPromisified(process.execPath, [
+		"--no-warnings",
+		"--import=./dist/register-transform.mjs",
+		fixturesPath("esm/esm.ts"),
+	]);
+
+	strictEqual(result.stderr, "");
+	match(result.stdout, /Hello from ESM TypeScript!/);
+	strictEqual(result.code, 0);
+});
+
+test("should work with .mts files using strip", async () => {
+	const result = await spawnPromisified(process.execPath, [
+		"--no-warnings",
+		"--import=./dist/register-strip.mjs",
+		fixturesPath("esm.mts"),
+	]);
+
+	strictEqual(result.stderr, "");
+	match(result.stdout, /Hello from ESM TypeScript!/);
+	strictEqual(result.code, 0);
+});
+
+test("should work with .mts files using transform", async () => {
+	const result = await spawnPromisified(process.execPath, [
+		"--no-warnings",
+		"--import=./dist/register-transform.mjs",
+		fixturesPath("esm.mts"),
+	]);
+
+	strictEqual(result.stderr, "");
+	match(result.stdout, /Hello from ESM TypeScript!/);
+	strictEqual(result.code, 0);
+});