diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php
index 23b0f4a..a363155 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Core\Config\Entity;
 
+use Drupal\Core\Config\Entity\Exception\ConfigEntityStorageClassException;
 use Drupal\Core\Entity\EntityType;
 use Drupal\Core\Config\ConfigPrefixLengthException;
 use Drupal\Component\Utility\String;
@@ -62,6 +63,10 @@ class ConfigEntityType extends EntityType {
 
   /**
    * {@inheritdoc}
+   *
+   * @throws \Drupal\Core\Config\Entity\Exception\ConfigEntityStorageClassException
+   *   Exception thrown when the provided class is not an instance of
+   *   \Drupal\Core\Config\Entity\ConfigEntityStorage.
    */
   public function __construct($definition) {
     // Ensure a default list cache tag is set; do this before calling the parent
@@ -74,6 +79,9 @@ public function __construct($definition) {
     // Always add a default 'uuid' key.
     $this->entity_keys['uuid'] = 'uuid';
     $this->entity_keys['langcode'] = 'langcode';
+    if (isset($this->handlers['storage'])) {
+      $this->checkStorageClass($this->handlers['storage']);
+    }
     $this->handlers += array(
       'storage' => 'Drupal\Core\Config\Entity\ConfigEntityStorage',
     );
@@ -139,4 +147,30 @@ public function getConfigDependencyKey() {
     return 'config';
   }
 
+  /**
+   * {@inheritdoc}
+   *
+   * @throws \Drupal\Core\Config\Entity\Exception\ConfigEntityStorageClassException
+   *   Exception thrown when the provided class is not an instance of
+   *   \Drupal\Core\Config\Entity\ConfigEntityStorage.
+   */
+  public function setStorageClass($class) {
+    $this->checkStorageClass($class);
+    parent::setStorageClass($class);
+  }
+
+  /**
+   * Checks that the provided class is an instance of ConfigEntityStorage.
+   *
+   * @param string $class
+   *   The class to check.
+   *
+   * @see \Drupal\Core\Config\Entity\ConfigEntityStorage.
+   */
+  protected function checkStorageClass($class) {
+    if (!is_a($class, 'Drupal\Core\Config\Entity\ConfigEntityStorage', TRUE)) {
+      throw new ConfigEntityStorageClassException(String::format('@class is not \Drupal\Core\Config\Entity\ConfigEntityStorage or it does not extend it', ['@class' => $class]));
+    }
+  }
+
 }
diff --git a/core/lib/Drupal/Core/Config/Entity/Exception/ConfigEntityStorageClassException.php b/core/lib/Drupal/Core/Config/Entity/Exception/ConfigEntityStorageClassException.php
new file mode 100644
index 0000000..d7c0f0c
--- /dev/null
+++ b/core/lib/Drupal/Core/Config/Entity/Exception/ConfigEntityStorageClassException.php
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Config\Entity\Exception\ConfigEntityStorageClassException.
+ */
+
+namespace Drupal\Core\Config\Entity\Exception;
+
+use Drupal\Core\Config\ConfigException;
+
+/**
+ * Thrown when a storage class is not an instance of ConfigEntityStorage.
+ */
+class ConfigEntityStorageClassException extends ConfigException {}
diff --git a/core/lib/Drupal/Core/Entity/KeyValueStore/KeyValueConfigEntityStorage.php b/core/lib/Drupal/Core/Entity/KeyValueStore/KeyValueConfigEntityStorage.php
deleted file mode 100644
index 858ff51..0000000
--- a/core/lib/Drupal/Core/Entity/KeyValueStore/KeyValueConfigEntityStorage.php
+++ /dev/null
@@ -1,65 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Entity\KeyValueStore\KeyValueConfigEntityStorage.
- */
-
-namespace Drupal\Core\Entity\KeyValueStore;
-
-use Drupal\Component\Uuid\UuidInterface;
-use Drupal\Core\Config\Entity\ConfigEntityStorageInterface;
-use Drupal\Core\Entity\EntityTypeInterface;
-use Drupal\Core\KeyValueStore\KeyValueStoreInterface;
-use Drupal\Core\Language\LanguageManagerInterface;
-use Symfony\Component\DependencyInjection\ContainerInterface;
-use Drupal\Core\Config\ConfigFactoryInterface;
-use Drupal\Core\Config\Entity\ConfigEntityInterface;
-
-/**
- * Provides a key value backend for configuration entities.
- */
-class KeyValueConfigEntityStorage extends KeyValueEntityStorage implements ConfigEntityStorageInterface {
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function getIDFromConfigName($config_name, $config_prefix) {
-    // @todo Implement and test. See https://www.drupal.org/node/2406645
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function createFromStorageRecord(array $values) {
-    // @todo Implement and test. See https://www.drupal.org/node/2406645
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function updateFromStorageRecord(ConfigEntityInterface $entity, array $values) {
-    // @todo Implement and test. See https://www.drupal.org/node/2406645
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function loadOverrideFree($id) {
-    // KeyValueEntityStorage does not support storing and retrieving overrides,
-    // it does not use the configuration factory. This is just a test method.
-    // See https://www.drupal.org/node/2393751.
-    return $this->load($id);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function loadMultipleOverrideFree(array $ids = NULL) {
-    // KeyValueEntityStorage does not support storing and retrieving overrides,
-    // it does not use the configuration factory. This is just a test method.
-    // See https://www.drupal.org/node/2393751.
-    return $this->loadMultiple($ids);
-  }
-
-}
diff --git a/core/modules/search/src/Entity/SearchPage.php b/core/modules/search/src/Entity/SearchPage.php
index 1a1af60..d8cfc41 100644
--- a/core/modules/search/src/Entity/SearchPage.php
+++ b/core/modules/search/src/Entity/SearchPage.php
@@ -24,7 +24,6 @@
  *   label = @Translation("Search page"),
  *   handlers = {
  *     "access" = "Drupal\search\SearchPageAccessControlHandler",
- *     "storage" = "Drupal\Core\Config\Entity\ConfigEntityStorage",
  *     "list_builder" = "Drupal\search\SearchPageListBuilder",
  *     "form" = {
  *       "add" = "Drupal\search\Form\SearchPageAddForm",
diff --git a/core/modules/system/src/Tests/KeyValueStore/KeyValueConfigEntityStorageTest.php b/core/modules/system/src/Tests/KeyValueStore/KeyValueConfigEntityStorageTest.php
deleted file mode 100644
index 1fe1ab6..0000000
--- a/core/modules/system/src/Tests/KeyValueStore/KeyValueConfigEntityStorageTest.php
+++ /dev/null
@@ -1,32 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\system\Tests\KeyValueStore\KeyValueConfigEntityStorageTest.
- */
-
-namespace Drupal\system\Tests\KeyValueStore;
-
-use Drupal\config\Tests\ConfigEntityTest;
-use Drupal\Core\Entity\KeyValueStore\KeyValueEntityStorage;
-
-/**
- * Tests KeyValueEntityStorage for config entities.
- *
- * @group KeyValueStore
- */
-class KeyValueConfigEntityStorageTest extends ConfigEntityTest {
-
-  /**
-   * {@inheritdoc}
-   */
-  const MAX_ID_LENGTH = KeyValueEntityStorage::MAX_ID_LENGTH;
-
-  /**
-   * Modules to enable.
-   *
-   * @var array
-   */
-  public static $modules = array('keyvalue_test');
-
-}
diff --git a/core/modules/system/tests/modules/keyvalue_test/keyvalue_test.info.yml b/core/modules/system/tests/modules/keyvalue_test/keyvalue_test.info.yml
index 41cfb33..01319ed 100644
--- a/core/modules/system/tests/modules/keyvalue_test/keyvalue_test.info.yml
+++ b/core/modules/system/tests/modules/keyvalue_test/keyvalue_test.info.yml
@@ -6,5 +6,4 @@ package: Testing
 version: VERSION
 hidden: true
 dependencies:
-  - config_test
   - entity_test
diff --git a/core/modules/system/tests/modules/keyvalue_test/keyvalue_test.module b/core/modules/system/tests/modules/keyvalue_test/keyvalue_test.module
index 74549db..d8c3666 100644
--- a/core/modules/system/tests/modules/keyvalue_test/keyvalue_test.module
+++ b/core/modules/system/tests/modules/keyvalue_test/keyvalue_test.module
@@ -10,9 +10,6 @@
  */
 function keyvalue_test_entity_type_alter(array &$entity_types) {
   /** @var $entity_types \Drupal\Core\Entity\EntityTypeInterface[] */
-  if (isset($entity_types['config_test'])) {
-    $entity_types['config_test']->setStorageClass('Drupal\Core\Entity\KeyValueStore\KeyValueConfigEntityStorage');
-  }
   if (isset($entity_types['entity_test_label'])) {
     $entity_types['entity_test_label']->setStorageClass('Drupal\Core\Entity\KeyValueStore\KeyValueEntityStorage');
     $entity_keys = $entity_types['entity_test_label']->getKeys();
diff --git a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityTypeTest.php b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityTypeTest.php
index 0af505d..d3dfc25 100644
--- a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityTypeTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityTypeTest.php
@@ -75,4 +75,38 @@ public function testConfigPrefixLengthValid() {
     $this->assertEquals($expected_prefix, $config_entity->getConfigPrefix());
   }
 
+  /**
+   * @covers ::__construct
+   */
+  public function testConstruct() {
+    $config_entity = new ConfigEntityType([
+      'id' => 'example_config_entity_type',
+    ]);
+    $this->assertEquals('Drupal\Core\Config\Entity\ConfigEntityStorage', $config_entity->getStorageClass());
+  }
+
+  /**
+   * @covers ::__construct
+   *
+   * @expectedException \Drupal\Core\Config\Entity\Exception\ConfigEntityStorageClassException
+   * @expectedExceptionMessage \Drupal\Core\Entity\KeyValueStore\KeyValueEntityStorage is not \Drupal\Core\Config\Entity\ConfigEntityStorage or it does not extend it
+   */
+  public function testConstructBadStorage() {
+    new ConfigEntityType([
+      'id' => 'example_config_entity_type',
+      'handlers' => ['storage' => '\Drupal\Core\Entity\KeyValueStore\KeyValueEntityStorage']
+    ]);
+  }
+
+  /**
+   * @covers ::setStorageClass
+   *
+   * @expectedException \Drupal\Core\Config\Entity\Exception\ConfigEntityStorageClassException
+   * @expectedExceptionMessage \Drupal\Core\Entity\KeyValueStore\KeyValueEntityStorage is not \Drupal\Core\Config\Entity\ConfigEntityStorage or it does not extend it
+   */
+  public function testSetStorageClass() {
+    $config_entity = $this->setUpConfigEntityType([]);
+    $config_entity->setStorageClass('\Drupal\Core\Entity\KeyValueStore\KeyValueEntityStorage');
+  }
+
 }