diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
index 95bcf58..b3e23ae 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
@@ -95,14 +95,10 @@ public function __construct(array $values, $entity_type) {
     // If needed, map the config keys to entity properties.
     $config_mapping = $this->getEntityType()->getConfigMapping();
     foreach ($values as $key => $value) {
+      // Check for a config mapping, otherwise use the default key.
       if (isset($config_mapping[$key])) {
-        $new_key = $config_mapping[$key];
-        $values[$new_key] = $value;
-        unset($values[$key]);
+        $key = $config_mapping[$key];
       }
-    }
-    // Set initial values.
-    foreach ($values as $key => $value) {
       $this->$key = $value;
     }
 
@@ -257,25 +253,17 @@ public static function sort(ConfigEntityInterface $a, ConfigEntityInterface $b)
   public function toArray() {
     $properties = array();
     $config_name = $this->getEntityType()->getConfigPrefix() . '.' . $this->id();
-    $config_mapping = $this->getEntityType()->getConfigMapping();
     $definition = $this->getTypedConfig()->getDefinition($config_name);
     if (!isset($definition['mapping'])) {
       throw new SchemaIncompleteException(String::format('Incomplete or missing schema for @config_name', array('@config_name' => $config_name)));
     }
-    $config_keys = array_keys($definition['mapping']);
-    if (empty($config_mapping)) {
-      // If no config mapping was defined, assume that the entity properties
-      // match the config keys.
-      $config_mapping = array_combine($config_keys, $config_keys);
-    }
-
     $id_key = $this->getEntityType()->getKey('id');
-    foreach ($config_keys as $name) {
-      if (!isset($config_mapping[$name])) {
-        continue;
+    $config_mapping = $this->getEntityType()->getConfigMapping();
+    foreach (array_keys($definition['mapping']) as $name) {
+      // Check for a config mapping, otherwise use the default name.
+      if (isset($config_mapping[$name])) {
+        $name = $config_mapping[$name];
       }
-
-      $name = $config_mapping[$name];
       // Special handling for IDs so that computed compound IDs work.
       // @see \Drupal\Core\Entity\EntityDisplayBase::id()
       if ($name == $id_key) {
diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php
index 15a9b51..845e3ee 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php
@@ -60,7 +60,7 @@ class ConfigEntityType extends EntityType {
    *
    * @var array
    */
-  protected $config_mapping;
+  protected $config_mapping = [];
 
   /**
    * {@inheritdoc}
diff --git a/core/lib/Drupal/Core/Entity/EntityType.php b/core/lib/Drupal/Core/Entity/EntityType.php
index c2b0b9b..a26ffc4 100644
--- a/core/lib/Drupal/Core/Entity/EntityType.php
+++ b/core/lib/Drupal/Core/Entity/EntityType.php
@@ -631,7 +631,7 @@ public function getConfigPrefix() {
    * {@inheritdoc}
    */
   public function getConfigMapping() {
-    return FALSE;
+    return [];
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Entity/EntityTypeInterface.php b/core/lib/Drupal/Core/Entity/EntityTypeInterface.php
index 5ccae81..fc100c7 100644
--- a/core/lib/Drupal/Core/Entity/EntityTypeInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityTypeInterface.php
@@ -592,9 +592,8 @@ public function getConfigPrefix();
    *
    * @todo Used for configuration entities only.
    *
-   * @return array|bool
-   *   An array mapping each config key to its entity property, or FALSE if
-   *   not a configuration entity type.
+   * @return array
+   *   An array mapping each config key to its entity property.
    */
   public function getConfigMapping();
 
diff --git a/core/modules/node/src/Entity/NodeType.php b/core/modules/node/src/Entity/NodeType.php
index defe45f..f3cff98 100644
--- a/core/modules/node/src/Entity/NodeType.php
+++ b/core/modules/node/src/Entity/NodeType.php
@@ -30,14 +30,9 @@
  *   admin_permission = "administer content types",
  *   config_prefix = "type",
  *   config_mapping = {
- *     "name" = "name",
- *     "type" = "type"
- *     "description" = "description"
- *     "help" = "help"
- *     "new_revision" = "newRevision"
- *     "preview_mode" = "previewMode"
- *     "display_submitted" = "displaySubmitted"
- *     "third_party_settings" = "third_party_settings"
+ *     "new_revision" = "newRevision",
+ *     "preview_mode" = "previewMode",
+ *     "display_submitted" = "displaySubmitted",
  *   },
  *   bundle_of = "node",
  *   entity_keys = {
diff --git a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
index 7af62e5..5feb644 100644
--- a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
@@ -7,9 +7,7 @@
 
 namespace Drupal\Tests\Core\Config\Entity;
 
-use Drupal\Component\Plugin\ConfigurablePluginInterface;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
-use Drupal\Component\Plugin\PluginBase;
 use Drupal\Core\Language\Language;
 use Drupal\Tests\Core\Plugin\Fixtures\TestConfigurablePlugin;
 use Drupal\Tests\UnitTestCase;
@@ -95,11 +93,6 @@ class ConfigEntityBaseUnitTest extends UnitTestCase {
    */
   protected function setUp() {
     $this->id = $this->randomMachineName();
-    $values = array(
-      'id' => $this->id,
-      'langcode' => 'en',
-      'uuid' => '3bb9ee60-bea5-4622-b89b-a63319d10b3a',
-    );
     $this->entityTypeId = $this->randomMachineName();
     $this->provider = $this->randomMachineName();
     $this->entityType = $this->getMock('\Drupal\Core\Entity\EntityTypeInterface');
@@ -136,7 +129,24 @@ protected function setUp() {
     $container->set('config.typed', $this->typedConfigManager);
     \Drupal::setContainer($container);
 
-    $this->entity = $this->getMockForAbstractClass('\Drupal\Core\Config\Entity\ConfigEntityBase', array($values, $this->entityTypeId));
+    $this->entity = $this->setUpEntity();
+  }
+
+  /**
+   * Sets up an entity object for testing.
+   *
+   * @param array $values
+   *   An array of values to pass to the entity constructor.
+   *
+   * @return \Drupal\Core\Config\Entity\ConfigEntityBase|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected function setUpEntity(array $values = []) {
+    $values += array(
+      'id' => $this->id,
+      'langcode' => 'en',
+      'uuid' => '3bb9ee60-bea5-4622-b89b-a63319d10b3a',
+    );
+    return $this->getMockForAbstractClass('\Drupal\Core\Config\Entity\ConfigEntityBase', array($values, $this->entityTypeId));
   }
 
   /**
@@ -467,4 +477,20 @@ public function testToArrayFallback() {
     $this->entity->toArray();
   }
 
+  /**
+   * @covers ::toArray
+   */
+  public function testToArrayConfigMapping() {
+    $this->typedConfigManager->expects($this->once())
+      ->method('getDefinition')
+      ->will($this->returnValue(['mapping' => ['id' => '', 'dependencies' => '', 'foo_bar' => '']]));
+    $this->entityType->expects($this->atLeastOnce())
+      ->method('getConfigMapping')
+      ->willReturn(['foo_bar' => 'fooBar']);
+    $entity = $this->setUpEntity(['foo_bar' => 5]);
+    $properties = $this->entity->toArray();
+    $this->assertInternalType('array', $properties);
+    $this->assertEquals(['id' => $entity->id(), 'dependencies' => [], 'fooBar' => 5], $properties);
+  }
+
 }