diff --git a/lib/Crypto/Drupal7.php b/lib/Crypto/Drupal7.php
index 567e342..85024f4 100644
--- a/lib/Crypto/Drupal7.php
+++ b/lib/Crypto/Drupal7.php
@@ -34,6 +34,14 @@ class Drupal7 extends Phpass
      */
     const DRUPAL_HASH_LENGTH = 55;
 
+    /**
+     * @inheritdoc
+     */
+    public function configuration()
+    {
+        return [];
+    }
+
     /**
      * @inheritdoc
      */