diff --git a/src/passport.service.ts b/src/passport.service.ts
index 453d306..b9b82d0 100644
--- a/src/passport.service.ts
+++ b/src/passport.service.ts
@@ -1,7 +1,7 @@
 import { Inject, Injectable } from '@nestjs/common'
 
 import { PASSPORT_OPTIONS } from './constants'
-import { PassportOptions } from './interfaces'
+import { PassportOptions, VerifyResult } from './interfaces'
 import {
   base64UrlDecode,
   base64UrlEncode,
@@ -47,7 +47,7 @@ export class PassportService {
     return [userPart, iatPart, extPart, hmac].join(PassportService.EXTERNAL_SEP)
   }
 
-  public verify(token: string) {
+  public verify(token: string): VerifyResult {
     const parts = token.split(PassportService.EXTERNAL_SEP)
 
     if (parts.length !== 4) {