diff --git a/core/config/schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
index 800601f..f482e92 100644
--- a/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
@@ -268,6 +268,9 @@ config_entity:
     uuid:
       type: string
       label: 'UUID'
+    langcode:
+      type: string
+      label: 'Language code'
     status:
       type: boolean
       label: 'Status'
diff --git a/core/modules/config/src/Tests/ConfigImportUITest.php b/core/modules/config/src/Tests/ConfigImportUITest.php
index 68f8b78..4f3aea5 100644
--- a/core/modules/config/src/Tests/ConfigImportUITest.php
+++ b/core/modules/config/src/Tests/ConfigImportUITest.php
@@ -60,8 +60,8 @@ function testImport() {
 
     // Create new config entity.
     $original_dynamic_data = array(
-      'langcode' => \Drupal::languageManager()->getDefaultLanguage()->getId(),
       'uuid' => '30df59bd-7b03-4cf7-bb35-d42fc49f0651',
+      'langcode' => \Drupal::languageManager()->getDefaultLanguage()->getId(),
       'status' => TRUE,
       'dependencies' => array(),
       'id' => 'new',
@@ -367,8 +367,8 @@ function testImportErrorLog() {
     $uuid = $this->container->get('uuid');
 
     $values_primary = array(
-      'langcode' => 'en',
       'uuid' => $uuid->generate(),
+      'langcode' => 'en',
       'status' => TRUE,
       'dependencies' => array(),
       'id' => 'primary',
@@ -381,8 +381,8 @@ function testImportErrorLog() {
     );
     $staging->write($name_primary, $values_primary);
     $values_secondary = array(
-      'langcode' => 'en',
       'uuid' => $uuid->generate(),
+      'langcode' => 'en',
       'status' => TRUE,
       // Add a dependency on primary, to ensure that is synced first.
       'dependencies' => array(
diff --git a/core/modules/config/src/Tests/ConfigImporterTest.php b/core/modules/config/src/Tests/ConfigImporterTest.php
index 01ae40e..a6b2312 100644
--- a/core/modules/config/src/Tests/ConfigImporterTest.php
+++ b/core/modules/config/src/Tests/ConfigImporterTest.php
@@ -165,8 +165,8 @@ function testNew() {
 
     // Create new config entity.
     $original_dynamic_data = array(
-      'langcode' => \Drupal::languageManager()->getDefaultLanguage()->getId(),
       'uuid' => '30df59bd-7b03-4cf7-bb35-d42fc49f0651',
+      'langcode' => \Drupal::languageManager()->getDefaultLanguage()->getId(),
       'status' => TRUE,
       'dependencies' => array(),
       'id' => 'new',
diff --git a/core/modules/config/src/Tests/ConfigSchemaTest.php b/core/modules/config/src/Tests/ConfigSchemaTest.php
index 214ecbd..cf7cc08 100644
--- a/core/modules/config/src/Tests/ConfigSchemaTest.php
+++ b/core/modules/config/src/Tests/ConfigSchemaTest.php
@@ -96,14 +96,14 @@ function testSchemaMapping() {
     $expected = array();
     $expected['label'] = 'Maintenance mode';
     $expected['class'] = '\Drupal\Core\Config\Schema\Mapping';
-    $expected['mapping']['langcode'] = array(
-      'label' => 'Language code',
-      'type' => 'string',
-    );
     $expected['mapping']['message'] = array(
       'label' =>  'Message to display when in maintenance mode',
       'type' => 'text',
     );
+    $expected['mapping']['langcode'] = array(
+      'label' => 'Language code',
+      'type' => 'string',
+    );
     $expected['type'] = 'system.maintenance';
     $expected['definition_class'] = '\Drupal\Core\TypedData\MapDataDefinition';
     $this->assertEqual($definition, $expected, 'Retrieved the right metadata for system.maintenance');
@@ -152,11 +152,11 @@ function testSchemaMapping() {
     $expected['label'] = 'Image style';
     $expected['class'] = '\Drupal\Core\Config\Schema\Mapping';
     $expected['definition_class'] = '\Drupal\Core\TypedData\MapDataDefinition';
-    $expected['mapping']['langcode']['type'] = 'string';
-    $expected['mapping']['langcode']['label'] = 'Language code';
     $expected['mapping']['name']['type'] = 'string';
     $expected['mapping']['uuid']['type'] = 'string';
     $expected['mapping']['uuid']['label'] = 'UUID';
+    $expected['mapping']['langcode']['type'] = 'string';
+    $expected['mapping']['langcode']['label'] = 'Language code';
     $expected['mapping']['status']['type'] = 'boolean';
     $expected['mapping']['status']['label'] = 'Status';
     $expected['mapping']['dependencies']['type'] = 'config_dependencies';
diff --git a/core/modules/language/config/schema/language.schema.yml b/core/modules/language/config/schema/language.schema.yml
index 20f9043..5e3f55b 100644
--- a/core/modules/language/config/schema/language.schema.yml
+++ b/core/modules/language/config/schema/language.schema.yml
@@ -74,7 +74,6 @@ language.negotiation:
       type: string
       label: 'Selected language'
 
-# @todo top level type cannot be an entity
 language.mappings:
   type: config_object
   label: 'Language mapping'