diff --git a/node/node.d.ts b/node/node.d.ts
index 282120dc65..be3813ade4 100644
--- a/node/node.d.ts
+++ b/node/node.d.ts
@@ -1110,7 +1110,7 @@ declare module "crypto" {
         setPrivateKey(public_key: string, encoding?: string): void;
     }
     export function getDiffieHellman(group_name: string): DiffieHellman;
-    export function pbkdf2(password: string, salt: string, iterations: number, keylen: number, callback: (err: Error, derivedKey: string) => any): void;
+    export function pbkdf2(password: string, salt: string, iterations: number, keylen: number, callback: (err: Error, derivedKey: Buffer) => any): void;
     export function pbkdf2Sync(password: string, salt: string, iterations: number, keylen: number) : Buffer;
     export function randomBytes(size: number): Buffer;
     export function randomBytes(size: number, callback: (err: Error, buf: Buffer) =>void ): void;