diff --git a/index.d.ts b/index.d.ts
index c394967..5adf7f5 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -48,7 +48,7 @@ interface Hmac {
    *
    * @param secretKey The Secret Key
    */
-  create(secretKey: string): Hasher;
+  create(secretKey: string | number[]): Hasher;
 
   /**
    * Create a hash object and hash message using a secret key