diff --git a/src/authCallback.ts b/src/authCallback.ts
index fe0b744..2b17f37 100644
--- a/src/authCallback.ts
+++ b/src/authCallback.ts
@@ -5,7 +5,7 @@ export const authCallback = () => new Router().get('/auth/callback', (ctx) => {
 	// eslint-disable-next-line camelcase
 	const { access_token } = ctx.request.query;
 
-	const clean = DOMPurify.sanitize(access_token);
+        const clean = (access_token: string): string => DOMPurify.sanitize(access_token);
 	
 	// eslint-disable-next-line camelcase
 	if (!access_token) {
@@ -37,4 +37,4 @@ export const authCallback = () => new Router().get('/auth/callback', (ctx) => {
 
 	ctx.status = 200;
 })
-	.routes();
\ No newline at end of file
+	.routes();