diff --git a/services/web/app/src/Features/Project/ProjectController.js b/services/web/app/src/Features/Project/ProjectController.mjs
similarity index 100%
rename from services/web/app/src/Features/Project/ProjectController.js
rename to services/web/app/src/Features/Project/ProjectController.mjs
diff --git a/services/web/app/src/Features/Project/ProjectListController.mjs b/services/web/app/src/Features/Project/ProjectListController.mjs
index d2dc626d2f..6ae8f094c0 100644
--- a/services/web/app/src/Features/Project/ProjectListController.mjs
+++ b/services/web/app/src/Features/Project/ProjectListController.mjs
@@ -20,7 +20,7 @@ import Modules from '../../infrastructure/Modules.js'
 import { OError, V1ConnectionError } from '../Errors/Errors.js'
 import { User } from '../../models/User.js'
 import UserPrimaryEmailCheckHandler from '../User/UserPrimaryEmailCheckHandler.js'
-import UserController from '../User/UserController.js'
+import UserController from '../User/UserController.mjs'
 import NotificationsBuilder from '../Notifications/NotificationsBuilder.js'
 import GeoIpLookup from '../../infrastructure/GeoIpLookup.js'
 import SplitTestHandler from '../SplitTests/SplitTestHandler.js'
diff --git a/services/web/app/src/Features/User/UserController.js b/services/web/app/src/Features/User/UserController.mjs
similarity index 100%
rename from services/web/app/src/Features/User/UserController.js
rename to services/web/app/src/Features/User/UserController.mjs
diff --git a/services/web/app/src/router.mjs b/services/web/app/src/router.mjs
index 500ec4c691..1bd0b25237 100644
--- a/services/web/app/src/router.mjs
+++ b/services/web/app/src/router.mjs
@@ -1,7 +1,7 @@
 import AdminController from './Features/ServerAdmin/AdminController.js'
 import ErrorController from './Features/Errors/ErrorController.mjs'
 import Features from './infrastructure/Features.js'
-import ProjectController from './Features/Project/ProjectController.js'
+import ProjectController from './Features/Project/ProjectController.mjs'
 import ProjectApiController from './Features/Project/ProjectApiController.mjs'
 import ProjectListController from './Features/Project/ProjectListController.mjs'
 import SpellingController from './Features/Spelling/SpellingController.mjs'
@@ -19,7 +19,7 @@ import TagsController from './Features/Tags/TagsController.mjs'
 import NotificationsController from './Features/Notifications/NotificationsController.mjs'
 import CollaboratorsRouter from './Features/Collaborators/CollaboratorsRouter.mjs'
 import UserInfoController from './Features/User/UserInfoController.js'
-import UserController from './Features/User/UserController.js'
+import UserController from './Features/User/UserController.mjs'
 import UserEmailsController from './Features/User/UserEmailsController.js'
 import UserPagesController from './Features/User/UserPagesController.mjs'
 import TutorialController from './Features/Tutorial/TutorialController.mjs'
diff --git a/services/web/scripts/ensure_affiliations.mjs b/services/web/scripts/ensure_affiliations.mjs
index 98d9fd8b04..5ffc0695ee 100644
--- a/services/web/scripts/ensure_affiliations.mjs
+++ b/services/web/scripts/ensure_affiliations.mjs
@@ -1,5 +1,5 @@
 import { User } from '../app/src/models/User.js'
-import UserController from '../app/src/Features/User/UserController.js'
+import UserController from '../app/src/Features/User/UserController.mjs'
 import Logger from '@overleaf/logger'
 import pLimit from 'p-limit'
 
diff --git a/services/web/test/unit/src/Project/ProjectControllerTests.js b/services/web/test/unit/src/Project/ProjectController.test.mjs
similarity index 100%
rename from services/web/test/unit/src/Project/ProjectControllerTests.js
rename to services/web/test/unit/src/Project/ProjectController.test.mjs
diff --git a/services/web/test/unit/src/User/UserControllerTests.js b/services/web/test/unit/src/User/UserController.test.mjs
similarity index 100%
rename from services/web/test/unit/src/User/UserControllerTests.js
rename to services/web/test/unit/src/User/UserController.test.mjs