diff --git a/src/lhisp-oauth-client.t.ts b/src/lhisp-oauth-client.t.ts
index 08e67ff..1e71b4d 100644
--- a/src/lhisp-oauth-client.t.ts
+++ b/src/lhisp-oauth-client.t.ts
@@ -30,7 +30,8 @@ export interface AccessToken {
     token_type: string;
     access_token: string;
     expires_in: number;
-    created_at: number;
+    scope?: string;
+    created_at?: number;
 }
 
 export enum GrantType {
diff --git a/src/lhisp-oauth-client.ts b/src/lhisp-oauth-client.ts
index 033d8e2..66e393c 100644
--- a/src/lhisp-oauth-client.ts
+++ b/src/lhisp-oauth-client.ts
@@ -70,8 +70,8 @@ export default class LhispOauthClient {
 
     isTokenValid(token: AccessToken){
         if(!token) return false;
-        const now = Date.now()
-        const timeDiff = (now - token.created_at) / 1000;
+        if(!token.created_at) return false;
+        const timeDiff = (Date.now() - token.created_at) / 1000;
         return timeDiff < token.expires_in - 10;
     }