diff --git a/core/lib/Drupal/Core/Entity/EntityDisplayBase.php b/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
index a518209..4de891a 100644
--- a/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
@@ -122,7 +122,7 @@ public function __construct(array $values, $entity_type) {
       throw new \InvalidArgumentException('Missing required properties for an EntityDisplay entity.');
     }
 
-    if (!$this->entityManager()->getDefinition($values['targetEntityType']) instanceof ContentEntityTypeInterface) {
+    if (!$this->entityManager()->getDefinition($values['targetEntityType'])->isSubclassOf('\Drupal\Core\Entity\FieldableEntityInterface')) {
       throw new \InvalidArgumentException('EntityDisplay entities can only handle fieldable entity types.');
     }
 
diff --git a/core/lib/Drupal/Core/Entity/EntityType.php b/core/lib/Drupal/Core/Entity/EntityType.php
index fa1c6d0..60f3315 100644
--- a/core/lib/Drupal/Core/Entity/EntityType.php
+++ b/core/lib/Drupal/Core/Entity/EntityType.php
@@ -13,11 +13,6 @@
  * @ingroup entity_api
  */
 class EntityType implements EntityTypeInterface {
-
-  /*
-   * Defines EntityChangedInterface constant for internal usage
-   */
-  const ENTITY_TYPE_ENTITY_CHANGED_INTERFACE = 'Drupal\Core\Entity\EntityChangedInterface';
   
   use StringTranslationTrait;
 
@@ -306,7 +301,7 @@ public function __construct($definition) {
 
     // Automatically add the EntityChanged constraint if the entity type tracks
     // the changed time.
-    if (is_subclass_of($this->getClass(), self::ENTITY_TYPE_ENTITY_CHANGED_INTERFACE)) {
+    if (is_subclass_of($this->getClass(), EntityChangedInterface::class)) {
       $this->addConstraint('EntityChanged');
     }
 
diff --git a/core/lib/Drupal/Core/Field/FieldModuleUninstallValidator.php b/core/lib/Drupal/Core/Field/FieldModuleUninstallValidator.php
index dc75fb0..05300f1 100644
--- a/core/lib/Drupal/Core/Field/FieldModuleUninstallValidator.php
+++ b/core/lib/Drupal/Core/Field/FieldModuleUninstallValidator.php
@@ -44,7 +44,7 @@ public function validate($module_name) {
         // We skip entity types defined by the module as there must be no
         // content to be able to uninstall them anyway.
         // See \Drupal\Core\Entity\ContentUninstallValidator.
-        if ($entity_type->getProvider() != $module_name && $entity_type instanceof ContentEntityTypeInterface) {
+        if ($entity_type->getProvider() != $module_name && $entity_type->isSubclassOf('\Drupal\Core\Entity\FieldableEntityInterface')) {
           foreach ($this->entityManager->getFieldStorageDefinitions($entity_type_id) as $storage_definition) {
             if ($storage_definition->getProvider() == $module_name) {
               $storage = $this->entityManager->getStorage($entity_type_id);
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
index f2a3145..22d6e08 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -67,7 +67,7 @@ public static function propertyDefinitions(FieldStorageDefinitionInterface $fiel
     $target_type_info = \Drupal::entityManager()->getDefinition($settings['target_type']);
 
     $target_id_data_type = 'string';
-    if ($target_type_info instanceof ContentEntityTypeInterface) {
+    if ($target_type_info->isSubclassOf('\Drupal\Core\Entity\FieldableEntityInterface')) {
       $id_definition = \Drupal::entityManager()->getBaseFieldDefinitions($settings['target_type'])[$target_type_info->getKey('id')];
       if ($id_definition->getType() === 'integer') {
         $target_id_data_type = 'integer';
diff --git a/core/modules/comment/src/CommentManager.php b/core/modules/comment/src/CommentManager.php
index 8fdeb4e..49aef42 100644
--- a/core/modules/comment/src/CommentManager.php
+++ b/core/modules/comment/src/CommentManager.php
@@ -100,7 +100,7 @@ public function __construct(EntityManagerInterface $entity_manager, QueryFactory
    */
   public function getFields($entity_type_id) {
     $entity_type = $this->entityManager->getDefinition($entity_type_id);
-    if (!$entity_type instanceof ContentEntityTypeInterface) {
+    if (!$entity_type->isSubclassOf('\Drupal\Core\Entity\FieldableEntityInterface')) {
       // Early return, only content types can carry comment fields.
       return array();
     }