diff --git a/Config/Config.php b/Config/Config.php
index 7d57010..e8e3430 100644
--- a/Config/Config.php
+++ b/Config/Config.php
@@ -144,6 +144,6 @@ public function allowedPostTypes()
             );
         }
 
-        return $allowedPostTypes;
+        return \apply_filters('swiftype_allowed_post_types', $allowedPostTypes);
     }
 }
diff --git a/Document/Indexer.php b/Document/Indexer.php
index a2f3789..64026f8 100644
--- a/Document/Indexer.php
+++ b/Document/Indexer.php
@@ -16,6 +16,11 @@ class Indexer extends AbstractSwiftypeComponent
      */
     private $documentMapper;
 
+    /**
+     * @var string[]
+     */
+    private static $FORBIDDEN_POST_TYPES = ['attachment'];
+
     /**
      * Constructor.
      */
@@ -23,9 +28,22 @@ public function __construct()
     {
         parent::__construct();
         $this->documentMapper = new Mapper();
+        \add_filter('swiftype_allowed_post_types', [$this, 'filterAllowedPostType']);
         \add_action('swiftype_engine_loaded', [$this, 'installHooks']);
     }
 
+    /**
+     * Filter out forbiden post types fron indexing.
+     *
+     * @param string[] $allowedPostTypes
+     *
+     * @return string[]
+     */
+    public function filterAllowedPostType($allowedPostTypes)
+    {
+        return \array_diff($allowedPostTypes, self::$FORBIDDEN_POST_TYPES);
+    }
+
     /**
      * Install hooks only when the engine is created (swiftype_engine_loaded).
      */
@@ -44,8 +62,8 @@ public function installHooks()
           \add_action('trashed_post', [$this, 'handleTrashedPost']);
 
 
-          add_action('swiftype_batch_post_index', [$this, 'handlePostBatchIndex']);
-          add_action('swiftype_batch_post_delete', [$this, 'handlePostBatchDelete']);
+          \add_action('swiftype_batch_post_index', [$this, 'handlePostBatchIndex']);
+          \add_action('swiftype_batch_post_delete', [$this, 'handlePostBatchDelete']);
         }
     }