diff --git a/core/lib/Drupal/Core/Entity/EntityTypeInterface.php b/core/lib/Drupal/Core/Entity/EntityTypeInterface.php
index 5963b37..87268f4 100644
--- a/core/lib/Drupal/Core/Entity/EntityTypeInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityTypeInterface.php
@@ -380,6 +380,8 @@ public function setAccessClass($class);
    *
    * @return bool
    *   TRUE if the entity type is a subclass of the class or interface.
+   *
+   * @deprecated in Drupal 8.0.x-dev, will be removed before Drupal 8.0.0
    */
   public function isSubclassOf($class);
 
diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index f06d608..eb041f5 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -14,7 +14,6 @@
 use Drupal\comment\Entity\Comment;
 use Drupal\comment\CommentManagerInterface;
 use Drupal\comment\Entity\CommentType;
-use Drupal\Core\Entity\ContentEntityTypeInterface;
 use Drupal\Core\Entity\FieldableEntityInterface;
 use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
 use Drupal\Component\Utility\SafeMarkup;
@@ -311,10 +310,6 @@ function comment_form_field_storage_config_edit_form_alter(&$form, FormStateInte
  * @see \Drupal\comment\Plugin\Field\FieldType\CommentItem::propertyDefinitions()
  */
 function comment_entity_storage_load($entities, $entity_type) {
-  // Comments can only be attached to content entities, so skip others.
-  if (!\Drupal::entityManager()->getDefinition($entity_type) instanceof ContentEntityTypeInterface) {
-    return;
-  }
   if (!\Drupal::service('comment.manager')->getFields($entity_type)) {
     // Do not query database when entity has no comment fields.
     return;
diff --git a/core/modules/comment/comment.views.inc b/core/modules/comment/comment.views.inc
index 69a1cec..6e68c7f 100644
--- a/core/modules/comment/comment.views.inc
+++ b/core/modules/comment/comment.views.inc
@@ -4,7 +4,6 @@
  * @file
  * Provide views data for comment.module.
  */
-use Drupal\Core\Entity\ContentEntityTypeInterface;
 
 /**
  * Implements hook_views_data_alter().
@@ -21,16 +20,15 @@ function comment_views_data_alter(&$data) {
     ),
   );
 
-  // Provide a integration for each entity type except comment.
+  // Provide a integration for each entity type with fields except comment.
   foreach (\Drupal::entityManager()->getDefinitions() as $entity_type_id => $entity_type) {
-    if ($entity_type_id == 'comment' || !$entity_type instanceof ContentEntityTypeInterface || !$entity_type->getBaseTable()) {
+    if ($entity_type_id == 'comment' || !$entity_type->getBaseTable()) {
       continue;
     }
-    $fields = \Drupal::service('comment.manager')->getFields($entity_type_id);
-    $base_table = $entity_type->getDataTable() ?: $entity_type->getBaseTable();
-    $args = array('@entity_type' => $entity_type_id);
 
-    if ($fields) {
+    if ($fields = \Drupal::service('comment.manager')->getFields($entity_type_id)) {
+      $base_table = $entity_type->getDataTable() ?: $entity_type->getBaseTable();
+      $args = array('@entity_type' => $entity_type_id);
       $data[$base_table]['comments_link'] = array(
         'field' => array(
           'title' => t('Add comment link'),
diff --git a/core/modules/comment/src/CommentManager.php b/core/modules/comment/src/CommentManager.php
index 46d2572..f1be1a8 100644
--- a/core/modules/comment/src/CommentManager.php
+++ b/core/modules/comment/src/CommentManager.php
@@ -107,6 +107,7 @@ public function __construct(EntityManagerInterface $entity_manager, QueryFactory
   public function getFields($entity_type_id) {
     $entity_type = $this->entityManager->getDefinition($entity_type_id);
     if (!$entity_type instanceof ContentEntityTypeInterface) {
+      // Early return, only content types can carry comment fields.
       return array();
     }
 
diff --git a/core/modules/comment/tests/src/Unit/CommentManagerTest.php b/core/modules/comment/tests/src/Unit/CommentManagerTest.php
index acdd57a..6cc8393 100644
--- a/core/modules/comment/tests/src/Unit/CommentManagerTest.php
+++ b/core/modules/comment/tests/src/Unit/CommentManagerTest.php
@@ -27,10 +27,6 @@ public function testGetFields() {
     $entity_type->expects($this->any())
       ->method('getClass')
       ->will($this->returnValue('Node'));
-    $entity_type->expects($this->any())
-      ->method('isSubclassOf')
-      ->with('\Drupal\Core\Entity\FieldableEntityInterface')
-      ->will($this->returnValue(TRUE));
 
     $entity_manager = $this->getMock('Drupal\Core\Entity\EntityManagerInterface');
 
diff --git a/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php b/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
index 5762e9e..c9e5fec 100644
--- a/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/EntityManagerTest.php
@@ -875,7 +875,7 @@ public function testGetFieldDefinitionsProvider() {
    *   A field definition object.
    */
   protected function setUpEntityWithFieldDefinition($custom_invoke_all = FALSE, $field_definition_id = 'id', $entity_keys = array()) {
-    $this->entityType = $this->getMock('Drupal\Core\Entity\EntityTypeInterface');
+    $this->entityType = $this->getMock('Drupal\Core\Entity\ContentEntityTypeInterface');
 
     $this->entity = $this->getMockBuilder('Drupal\Tests\Core\Entity\EntityManagerTestEntity')
       ->disableOriginalConstructor()
@@ -888,10 +888,6 @@ protected function setUpEntityWithFieldDefinition($custom_invoke_all = FALSE, $f
     $this->entityType->expects($this->any())
       ->method('getKeys')
       ->will($this->returnValue($entity_keys + array('default_langcode' => 'default_langcode')));
-    $this->entityType->expects($this->any())
-      ->method('isSubclassOf')
-      ->with($this->equalTo('\Drupal\Core\Entity\FieldableEntityInterface'))
-      ->will($this->returnValue(TRUE));
     $field_definition = $this->getMockBuilder('Drupal\Core\Field\BaseFieldDefinition')
       ->disableOriginalConstructor()
       ->getMock();