diff --git a/js/index.d.ts b/js/index.d.ts
index 4befff2..ef29ccc 100644
--- a/js/index.d.ts
+++ b/js/index.d.ts
@@ -1,4 +1,4 @@
 declare module 'erlpack' {
 	export function pack(data: any): Buffer;
-	export function unpack(data: Buffer): any; 
+	export function unpack<T = any>(data: Buffer): T; 
 }