diff --git a/index.d.ts b/index.d.ts
index 52ccff7..47e3a6e 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,9 +1,13 @@
+import { KeyLike } from 'crypto';
+
 export type TAlgorithm = 'HS256' | 'HS384' | 'HS512' | 'RS256';
 
 export interface IOptions {
   header: any;
 }
 
-export function decode(token: string, key: string, noVerify?: boolean, algorithm?: TAlgorithm): any;
+export function decode(token: string, key: string | Buffer, noVerify?: boolean, algorithm?: TAlgorithm): any;
+export function decode(token: string, key: KeyLike, noVerify: true): any;
+export function decode(token: string, key: KeyLike, noVerify: boolean, algorithm: TAlgorithm): any;
 
-export function encode(payload: any, key: string, algorithm?: TAlgorithm, options?: IOptions): string;
+export function encode(payload: any, key: KeyLike, algorithm?: TAlgorithm, options?: IOptions): string;