diff --git a/src/Model/GalleryImage.php b/src/Model/GalleryImage.php
index f49ec8e..1dac5b4 100644
--- a/src/Model/GalleryImage.php
+++ b/src/Model/GalleryImage.php
@@ -61,6 +61,11 @@ class GalleryImage extends BaseElementObject
         'Content',
     );
 
+    /**
+     * @var string
+     */
+    private static $default_sort = 'SortOrder';
+
     /**
      * @var string
      */