diff --git a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
index a4624b4..e436c8b 100644
--- a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
+++ b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\rest\Plugin\rest\resource;
 
+use Drupal\Core\Config\Entity\ConfigEntityType;
 use Drupal\Core\Entity\EntityTypeManager;
 use Drupal\Core\Entity\FieldableEntityInterface;
 use Drupal\Core\Entity\EntityInterface;
@@ -331,10 +332,7 @@ public function availableMethods() {
    */
   protected function isConfigEntityResource() {
     $entity_type_id = $this->getPluginDefinition()['entity_type'];
-    $entity_type = $this->entityTypeManager->getDefinition($entity_type_id);
-    $class = $entity_type->getClass();
-    $interfaces = class_implements($class);
-    return in_array('Drupal\Core\Config\Entity\ConfigEntityInterface', $interfaces);
+    return $this->entityTypeManager->getDefinition($entity_type_id) instanceof ConfigEntityType;
   }
 
 }
diff --git a/core/modules/rest/src/Tests/RESTTestBase.php b/core/modules/rest/src/Tests/RESTTestBase.php
index 61dceec..4afbf94 100644
--- a/core/modules/rest/src/Tests/RESTTestBase.php
+++ b/core/modules/rest/src/Tests/RESTTestBase.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\rest\Tests;
 
+use Drupal\Core\Config\Entity\ConfigEntityType;
 use Drupal\node\NodeInterface;
 use Drupal\simpletest\WebTestBase;
 
@@ -377,10 +378,7 @@ protected function entityPermissions($entity_type_id, $operation) {
 
           default:
             return ['administer users'];
-
         }
-      case 'field_storage_config':
-        return ['administer node fields'];
 
       default:
         if ($this->isConfigEntity($entity_type_id)) {
@@ -464,10 +462,7 @@ protected function assertResponseBody($expected, $message = '', $group = 'REST R
    *   TRUE if the entity is a Config Entity, FALSE otherwise.
    */
   protected function isConfigEntity($entity_type_id) {
-    $entity_type = \Drupal::entityTypeManager()->getDefinition($entity_type_id);
-    $class = $entity_type->getClass();
-    $interfaces = class_implements($class);
-    return in_array('Drupal\Core\Config\Entity\ConfigEntityInterface', $interfaces);
+    return \Drupal::entityTypeManager()->getDefinition($entity_type_id) instanceof ConfigEntityType;
   }
 
   /**
@@ -498,14 +493,6 @@ protected function configEntityValues($entity_type_id) {
       case 'block':
         $values['plugin'] = 'system_powered_by_block';
         break;
-
-      case 'field_storage_config':
-        $values += [
-          'field_name' => strtolower($this->randomMachineName()),
-          'type' => 'boolean',
-          'entity_type' => 'node',
-        ];
-        break;
     }
     return $values;
   }
diff --git a/core/modules/rest/src/Tests/ReadTest.php b/core/modules/rest/src/Tests/ReadTest.php
index 78f0eec..fb455d2 100644
--- a/core/modules/rest/src/Tests/ReadTest.php
+++ b/core/modules/rest/src/Tests/ReadTest.php
@@ -26,8 +26,6 @@ class ReadTest extends RESTTestBase {
     'config_test',
     'taxonomy',
     'block',
-    'field',
-    'field_ui',
   ];
 
   /**
@@ -42,7 +40,6 @@ public function testRead() {
       'config_test',
       'taxonomy_vocabulary',
       'block',
-      'field_storage_config',
       'user_role',
     ];
     foreach ($entity_types as $entity_type) {