diff --git a/backend/src/app.ts b/backend/src/app.ts
index deb22095..defed5b2 100644
--- a/backend/src/app.ts
+++ b/backend/src/app.ts
@@ -11,8 +11,8 @@ import submissionRouter from './routes/submission.js';
 import classRouter from './routes/class.js';
 import questionRouter from './routes/question.js';
 import authRouter from './routes/auth.js';
-import {authenticateUser} from "./middleware/auth/auth";
-import cors from "./middleware/cors";
+import {authenticateUser} from "./middleware/auth/auth.js";
+import cors from "./middleware/cors.js";
 
 const app: Express = express();
 const port: string | number = getNumericEnvVar(EnvVars.Port);
diff --git a/backend/src/controllers/auth.ts b/backend/src/controllers/auth.ts
index 800c3b99..14c614a5 100644
--- a/backend/src/controllers/auth.ts
+++ b/backend/src/controllers/auth.ts
@@ -1,9 +1,4 @@
-import {EnvVars, getEnvVar} from "../util/envvars";
-
-type FrontendAuthConfig = {
-    student: FrontendIdpConfig,
-    teacher: FrontendIdpConfig
-}
+import {EnvVars, getEnvVar} from "../util/envvars.js";
 
 type FrontendIdpConfig = {
     authority: string,
@@ -12,6 +7,11 @@ type FrontendIdpConfig = {
     responseType: string
 }
 
+type FrontendAuthConfig = {
+    student: FrontendIdpConfig,
+    teacher: FrontendIdpConfig
+}
+
 const SCOPE = "openid profile email";
 const RESPONSE_TYPE = "code";
 
diff --git a/backend/src/middleware/auth/auth.ts b/backend/src/middleware/auth/auth.ts
index d06e6df2..ca564d8b 100644
--- a/backend/src/middleware/auth/auth.ts
+++ b/backend/src/middleware/auth/auth.ts
@@ -5,7 +5,7 @@ import jwksClient from 'jwks-rsa';
 import * as express from "express";
 import * as jwt from "jsonwebtoken";
 import {AuthenticatedRequest} from "./authenticated-request.js";
-import {AuthenticationInfo} from "./authentication-info";
+import {AuthenticationInfo} from "./authentication-info.js";
 
 function createJwksClient(uri: string): jwksClient.JwksClient {
     return jwksClient({
diff --git a/backend/src/middleware/auth/authenticated-request.ts b/backend/src/middleware/auth/authenticated-request.ts
index b29cfbac..275b2d19 100644
--- a/backend/src/middleware/auth/authenticated-request.ts
+++ b/backend/src/middleware/auth/authenticated-request.ts
@@ -1,6 +1,6 @@
 import { Request } from "express";
 import { JwtPayload } from "jsonwebtoken";
-import {AuthenticationInfo} from "./authentication-info";
+import {AuthenticationInfo} from "./authentication-info.js";
 
 export interface AuthenticatedRequest extends Request {
     // Properties are optional since the user is not necessarily authenticated.
diff --git a/backend/src/middleware/cors.ts b/backend/src/middleware/cors.ts
index 6f59f600..88104fb5 100644
--- a/backend/src/middleware/cors.ts
+++ b/backend/src/middleware/cors.ts
@@ -1,5 +1,5 @@
 import cors from "cors";
-import {EnvVars, getEnvVar} from "../util/envvars";
+import {EnvVars, getEnvVar} from "../util/envvars.js";
 
 export default cors({
     origin: getEnvVar(EnvVars.CorsAllowedOrigins).split(','),
diff --git a/backend/src/routes/auth.ts b/backend/src/routes/auth.ts
index 14f9364b..57af3a7d 100644
--- a/backend/src/routes/auth.ts
+++ b/backend/src/routes/auth.ts
@@ -1,6 +1,6 @@
 import express from 'express'
-import {getFrontendAuthConfig} from "../controllers/auth";
-import {authenticatedOnly, studentsOnly, teachersOnly} from "../middleware/auth/auth";
+import {getFrontendAuthConfig} from "../controllers/auth.js";
+import {authenticatedOnly, studentsOnly, teachersOnly} from "../middleware/auth/auth.js";
 const router = express.Router();
 
 // returns auth configuration for frontend