diff --git a/backend/routes/auth/login.ts b/backend/routes/auth/login.ts
index da4c306..fae08c4 100644
--- a/backend/routes/auth/login.ts
+++ b/backend/routes/auth/login.ts
@@ -37,7 +37,12 @@ router.post("/", async (req, res) => {
 	user.updatedAt = new Date();
 	await user.save();
 
-	const token = generateAuthToken(user);
+	const token = generateAuthToken({
+		_id: user._id,
+		username: user.username,
+		key: process.env.JWT_SECRET_KEY as string
+	});
+
 	res.status(200).json({
 		msg: `User ${user.username} logged in successfully!`,
 		token: token
diff --git a/backend/utils/generateToken.js b/backend/utils/generateToken.js
deleted file mode 100644
index 2690b5e..0000000
--- a/backend/utils/generateToken.js
+++ /dev/null
@@ -1,19 +0,0 @@
-import jwt from "jsonwebtoken";
-import dotenv from "dotenv";
-
-dotenv.config();
-
-const generateAuthToken = (user) => {
-	const jwtSecretKey = process.env.JWT_SECRET_KEY;
-	const token = jwt.sign(
-		{
-			_id: user._id,
-			username: user.username
-		},
-		jwtSecretKey
-	);
-
-	return token;
-};
-
-export default generateAuthToken;
diff --git a/backend/utils/generateToken.ts b/backend/utils/generateToken.ts
new file mode 100644
index 0000000..43b4074
--- /dev/null
+++ b/backend/utils/generateToken.ts
@@ -0,0 +1,29 @@
+import jwt, { Secret } from "jsonwebtoken";
+import dotenv from "dotenv";
+import User from "../models/user.js";
+
+dotenv.config();
+
+export interface UserTokenGenerator {
+	_id: string;
+	username: string;
+	key: Secret;
+}
+
+const generateAuthToken = (user: UserTokenGenerator) => {
+	if (!process.env.JWT_SECRET_KEY) {
+		throw new Error("JWT_SECRET_KEY is not defined.");
+	}
+	const jwtSecretKey = process.env.JWT_SECRET_KEY as Secret;
+	const token = jwt.sign(
+		{
+			_id: user._id,
+			username: user.username
+		},
+		jwtSecretKey
+	);
+
+	return token;
+};
+
+export default generateAuthToken;
diff --git a/backend/utils/setHeaders.js b/backend/utils/setHeaders.ts
similarity index 100%
rename from backend/utils/setHeaders.js
rename to backend/utils/setHeaders.ts