diff --git a/src/typescript.spec.ts b/src/typescript.spec.ts
index a7d164e..cb05a2d 100644
--- a/src/typescript.spec.ts
+++ b/src/typescript.spec.ts
@@ -1,7 +1,7 @@
 // typescript.spec.ts
 
 // it's ok to import test files from test code
-import testHello from './typescript.test';
+import testHello from './typescript.test.ts';
 testHello();
 
 // linting error is not reported because unicorn/no-anonymous-default-export is disabled
diff --git a/src/typescript.test.ts b/src/typescript.test.ts
index 103dceb..89688f4 100644
--- a/src/typescript.test.ts
+++ b/src/typescript.test.ts
@@ -7,7 +7,7 @@ import 'typescript';
 // eslint-disable-next-line n/no-restricted-import
 import 'fclone';
 
-import './typescript';
+import './typescript.ts';
 
 function testHello(_?: string): number {
   return 123 + 0xf;
diff --git a/src/typescript.ts b/src/typescript.ts
index e8dad2b..a35290b 100644
--- a/src/typescript.ts
+++ b/src/typescript.ts
@@ -18,7 +18,7 @@ import { format } from 'node:url';
 assert.ok(format !== undefined);
 
 // eslint-disable-next-line @checkdigit/no-test-import
-import testHello from './typescript.test';
+import testHello from './typescript.test.ts';
 testHello();
 
 // eslint-disable-next-line n/no-sync