diff --git a/src/attest.ts b/src/attest.ts
index 025761b..1907be7 100644
--- a/src/attest.ts
+++ b/src/attest.ts
@@ -6,7 +6,7 @@ import {
   createStorageRecord
 } from '@actions/attest'
 import { attachArtifactToImage, getRegistryCredentials } from '@sigstore/oci'
-import { formatSubjectDigest } from './subject'
+import { formatSubjectDigest } from './subject.js'
 import * as core from '@actions/core'
 import * as github from '@actions/github'
 
diff --git a/src/index.ts b/src/index.ts
index 890f747..5fc175c 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -2,7 +2,7 @@
  * The entrypoint for the action.
  */
 import * as core from '@actions/core'
-import { run, RunInputs } from './main'
+import { run, RunInputs } from './main.js'
 
 const inputs: RunInputs = {
   subjectPath: core.getInput('subject-path'),
diff --git a/src/main.ts b/src/main.ts
index fc4db78..c5ac73e 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -3,15 +3,15 @@ import * as github from '@actions/github'
 import fs from 'fs'
 import os from 'os'
 import path from 'path'
-import { AttestResult, SigstoreInstance, createAttestation } from './attest'
-import { SEARCH_PUBLIC_GOOD_URL } from './endpoints'
-import { PredicateInputs, predicateFromInputs } from './predicate'
-import * as style from './style'
+import { AttestResult, SigstoreInstance, createAttestation } from './attest.js'
+import { SEARCH_PUBLIC_GOOD_URL } from './endpoints.js'
+import { PredicateInputs, predicateFromInputs } from './predicate.js'
+import * as style from './style.js'
 import {
   SubjectInputs,
   formatSubjectDigest,
   subjectFromInputs
-} from './subject'
+} from './subject.js'
 
 import type { Subject } from '@actions/attest'