diff --git a/index.d.ts b/index.d.ts
index cedaca1..6b7d178 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -42,6 +42,20 @@ interface Hash {
    */
   (message: Message): string;
 
+  /**
+   * Hash and return ArrayBuffer.
+   *
+   * @param message The message you want to hash.
+   */
+  arrayBuffer(message: Message): ArrayBuffer;
+
+  /**
+   * Hash and return ArrayBuffer.
+   *
+   * @param message The message you want to hash.
+   */
+  buffer(message: Message): ArrayBuffer;
+
   /**
    * Create a hash object.
    */