diff --git a/types/index.d.ts b/types/index.d.ts
index f5084ac..01b9f89 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -183,13 +183,13 @@ declare namespace fastifyOauth2 {
         
         revokeAllToken(revokeToken: Token, httpOptions: Object | undefined): Promise<void>;
 
-        userinfo(tokenSetOrToken: Token | string): Promise<Object>;
+        userinfo<TUserInfo = Object>(tokenSetOrToken: Token | string): Promise<TUserInfo>;
 
-        userinfo(tokenSetOrToken: Token | string, userInfoExtraOptions: UserInfoExtraOptions | undefined): Promise<Object>;
+        userinfo<TUserInfo = Object>(tokenSetOrToken: Token | string, userInfoExtraOptions: UserInfoExtraOptions | undefined): Promise<TUserInfo>;
 
-        userinfo(tokenSetOrToken: Token | string, callback: (err: any, userinfo: Object) => void): void;
+        userinfo<TUserInfo = Object>(tokenSetOrToken: Token | string, callback: (err: any, userinfo: TUserInfo) => void): void;
 
-        userinfo(tokenSetOrToken: Token | string, userInfoExtraOptions: UserInfoExtraOptions | undefined, callback: (err: any, userinfo: Object) => void): void;
+        userinfo<TUserInfo = Object>(tokenSetOrToken: Token | string, userInfoExtraOptions: UserInfoExtraOptions | undefined, callback: (err: any, userinfo: TUserInfo) => void): void;
     }
     export type UserInfoExtraOptions = { method?: 'GET' | 'POST', via?: 'header' | 'body', params?: object };
     export const fastifyOauth2: FastifyOauth2
diff --git a/types/index.test-d.ts b/types/index.test-d.ts
index 7fc67a5..c3b2260 100644
--- a/types/index.test-d.ts
+++ b/types/index.test-d.ts
@@ -283,6 +283,7 @@ server.get('/testOauth/callback', async (request, reply) => {
     expectType<Promise<Object>>(server.testOAuthName.userinfo(token.token));
     expectType<Promise<Object>>(server.testOAuthName.userinfo(token.token.access_token));
     expectType<Object>(await server.testOAuthName.userinfo(token.token.access_token));
+    expectType<{a: string}>(await server.testOAuthName.userinfo<{a: string}>(token.token.access_token));
     expectType<void>(server.testOAuthName.userinfo(token.token.access_token, () => {}));
     expectType<void>(server.testOAuthName.userinfo(token.token.access_token, undefined, () => {}));
     expectAssignable<UserInfoExtraOptions>({ method: 'GET', params: {}, via: 'header' });