diff --git a/lib/Drupal/search_api/Entity/Index.php b/lib/Drupal/search_api/Entity/Index.php
index 0c05187..d334f71 100644
--- a/lib/Drupal/search_api/Entity/Index.php
+++ b/lib/Drupal/search_api/Entity/Index.php
@@ -545,6 +545,8 @@ class Index extends ConfigEntityBase implements IndexInterface {
 
         // Don't add the additional 'entity' property for entity reference
         // fields which don't target a content entity type.
+        // @todo Try to see if there's a better way of doing this check when
+        // https://drupal.org/node/2228721 gets fixed.
         if ($property instanceof FieldItemDataDefinition && $property->getDataType() == 'field_item:entity_reference') {
           $entity_type = $this->entityManager()->getDefinition($property->getSetting('target_type'));
           if (!$entity_type->isSubclassOf('\Drupal\Core\Entity\ContentEntityInterface')) {