diff --git a/includes/transformer/class-post.php b/includes/transformer/class-post.php
index 69dcf89..6f1fed3 100644
--- a/includes/transformer/class-post.php
+++ b/includes/transformer/class-post.php
@@ -28,6 +28,13 @@ class Post {
 	 */
 	protected $wp_post;
 
+	/**
+	 * Attachment images, used in the content.
+	 *
+	 * @var array
+	 */
+	protected $attachments = array();
+
 	/**
 	 * The Allowed Tags, used in the content.
 	 *