diff --git a/src/cjs/api/module-resolve-filename/index.ts b/src/cjs/api/module-resolve-filename/index.ts
index 9e88026a2..46454a54d 100644
--- a/src/cjs/api/module-resolve-filename/index.ts
+++ b/src/cjs/api/module-resolve-filename/index.ts
@@ -78,7 +78,13 @@ export const createResolveFilename = (
 
 	nextResolveSimple = createTsExtensionResolver(
 		nextResolveSimple,
-		Boolean(parent?.filename && tsExtensionsPattern.test(parent.filename)),
+		Boolean(
+			// If register.namespace is used (e.g. tsx.require())
+			namespace
+
+			// If parent is a TS file
+			|| (parent?.filename && tsExtensionsPattern.test(parent.filename)),
+		),
 	);
 
 	nextResolveSimple = createImplicitResolver(nextResolveSimple);
diff --git a/tests/specs/api.ts b/tests/specs/api.ts
index 4bfb85614..edb02ee20 100644
--- a/tests/specs/api.ts
+++ b/tests/specs/api.ts
@@ -2,6 +2,7 @@ import path from 'node:path';
 import { execaNode } from 'execa';
 import { testSuite, expect } from 'manten';
 import { createFixture } from 'fs-fixture';
+import { outdent } from 'outdent';
 import {
 	tsxCjsPath,
 	tsxCjsApiPath,
@@ -11,7 +12,6 @@ import {
 	type NodeApis,
 } from '../utils/tsx.js';
 import { createPackageJson, createTsconfig, expectErrors } from '../fixtures.js';
-import { outdent } from 'outdent';
 
 const tsFiles = {
 	'file.ts': outdent`
@@ -266,7 +266,8 @@ export default testSuite(({ describe }, node: NodeApis) => {
 						...tsFiles,
 					});
 
-					const { stdout } = await execaNode(fixture.getPath('require.cjs'), [], {
+					const { stdout } = await execaNode('./require.cjs', [], {
+						cwd: fixture.path,
 						nodePath: node.path,
 						nodeOptions: [],
 					});