diff --git a/core/modules/language/migration_templates/d6_default_language.yml b/core/modules/language/migration_templates/d6_default_language.yml
deleted file mode 100644
index 8c37415..0000000
--- a/core/modules/language/migration_templates/d6_default_language.yml
+++ /dev/null
@@ -1,23 +0,0 @@
-id: d6_default_language
-label: Default language
-migration_tags:
-  - Drupal 6
-source:
-  plugin: default_language
-process:
-  default_langcode:
-    -
-      plugin: callback
-      callable: get_object_vars
-      source: language_default
-    -
-      plugin: extract
-      index:
-        - language
-
-destination:
-  plugin: config
-  config_name: system.site
-migration_dependencies:
-  required:
-    - language
diff --git a/core/modules/language/migration_templates/default_language.yml b/core/modules/language/migration_templates/default_language.yml
new file mode 100644
index 0000000..d7e52ad
--- /dev/null
+++ b/core/modules/language/migration_templates/default_language.yml
@@ -0,0 +1,25 @@
+id: default_language
+label: Default language
+migration_tags:
+  - Drupal 6
+  - Drupal 7
+source:
+  plugin: variable
+  variables:
+    - language_default
+process:
+  default_langcode:
+    -
+      plugin: callback
+      callable: get_object_vars
+      source: language_default
+    -
+      plugin: extract
+      index:
+        - language
+destination:
+  plugin: default_langcode
+  config_name: system.site
+migration_dependencies:
+  required:
+    - language
diff --git a/core/modules/language/src/Plugin/migrate/destination/DefaultLangcode.php b/core/modules/language/src/Plugin/migrate/destination/DefaultLangcode.php
new file mode 100644
index 0000000..47c44c0
--- /dev/null
+++ b/core/modules/language/src/Plugin/migrate/destination/DefaultLangcode.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace Drupal\language\Plugin\migrate\destination;
+
+use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\migrate\MigrateException;
+use Drupal\migrate\Plugin\migrate\destination\Config;
+use Drupal\migrate\Row;
+
+/**
+ * Provides a destination plugin for the default langcode config.
+ *
+ * @MigrateDestination(
+ *   id = "default_langcode"
+ * )
+ */
+class DefaultLangcode extends Config {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function import(Row $row, array $old_destination_id_values = array()) {
+    $destination = $row->getDestination();
+
+    // Check if the language exists.
+    if (ConfigurableLanguage::load($destination['default_langcode']) === NULL) {
+      throw new MigrateException(sprintf("The language '%s' does not exist on this site.", $destination['default_langcode']));
+    }
+
+    $this->config->set('default_langcode', $destination['default_langcode']);
+    $this->config->save();
+    return [$this->config->getName()];
+  }
+
+}
diff --git a/core/modules/language/src/Plugin/migrate/source/DefaultLanguage.php b/core/modules/language/src/Plugin/migrate/source/DefaultLanguage.php
deleted file mode 100644
index 2d0d650..0000000
--- a/core/modules/language/src/Plugin/migrate/source/DefaultLanguage.php
+++ /dev/null
@@ -1,83 +0,0 @@
-<?php
-
-namespace Drupal\language\Plugin\migrate\source;
-
-use Drupal\Core\Entity\EntityManagerInterface;
-use Drupal\Core\State\StateInterface;
-use Drupal\language\Entity\ConfigurableLanguage;
-use Drupal\migrate\MigrateException;
-use Drupal\migrate\Plugin\MigrationInterface;
-use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
-
-/**
- * Default language variable from database.
- *
- * This source class is used exclusively for the language_default variable.
- *
- * @MigrateSource(
- *   id = "default_language",
- * )
- */
-class DefaultLanguage extends DrupalSqlBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, StateInterface $state, EntityManagerInterface $entity_manager) {
-    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $state, $entity_manager);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function initializeIterator() {
-    return new \ArrayIterator(array($this->values()));
-  }
-
-  /**
-   * Return the value of the language_default variable.
-   *
-   * @return array
-   *   An associative array where the key is the variable name
-   *   and the value is the value found in the database.
-   */
-  protected function values() {
-    // Create an ID field so we can record migration in the map table.
-    $values['id'] = 'language_default';
-    $results = $this->prepareQuery()->execute()->fetchAllKeyed();
-    $language_default = unserialize($results['language_default']);
-
-    // Check if the language exists, fail otherwise.
-    if (ConfigurableLanguage::load($language_default->language) === NULL) {
-      throw new MigrateException("The language $language_default->language does not exists on this site.");
-    }
-
-    return $values + ['language_default' => $language_default];
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function query() {
-    return $this->getDatabase()
-      ->select('variable', 'v')
-      ->fields('v', array('name', 'value'))
-      ->condition('name', 'language_default');
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function fields() {
-    return ['language_default' => 'language_default'];
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getIds() {
-    $ids['id']['type'] = 'string';
-    return $ids;
-  }
-
-}
diff --git a/core/modules/language/src/Tests/Migrate/d6/MigrateDefaultLanguageTest.php b/core/modules/language/src/Tests/Migrate/d6/MigrateDefaultLanguageTest.php
deleted file mode 100644
index 9f7c7c9..0000000
--- a/core/modules/language/src/Tests/Migrate/d6/MigrateDefaultLanguageTest.php
+++ /dev/null
@@ -1,61 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\language\Tests\Migrate\d6\MigrateDefaultLanguageTest.
- */
-
-namespace Drupal\language\Tests\Migrate\d6;
-
-use Drupal\language\Entity\ConfigurableLanguage;
-use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
-
-/**
- * Tests the default language variable migration.
- *
- * @group migrate_drupal_6
- */
-class MigrateDefaultLanguageTest extends MigrateDrupal6TestBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public static $modules = ['language'];
-
-  /**
-   * Tests the migration of the language_default variable to the
-   * system.site.default_langcode config key, with an existing language.
-   */
-  public function testMigrationWithExistingLanguage() {
-    $this->doTestMigration('fr');
-  }
-
-  /**
-   * Tests the migration of the language_default variable to the
-   * system.site.default_langcode config key, with a non-existent language.
-   */
-  public function testMigrationWithNonExistentLanguage() {
-    $this->doTestMigration('tv');
-  }
-
-  /**
-   * Helper method to test the migration.
-   */
-  protected function doTestMigration($langcode) {
-    // The default language of the test fixture is English. Change it to
-    // something else before migrating, to be sure that the source site
-    // default language is migrated.
-    $value = 'O:8:"stdClass":11:{s:8:"language";s:2:"' . $langcode . '";s:4:"name";s:6:"French";s:6:"native";s:6:"French";s:9:"direction";s:1:"0";s:7:"enabled";i:1;s:7:"plurals";s:1:"0";s:7:"formula";s:0:"";s:6:"domain";s:0:"";s:6:"prefix";s:0:"";s:6:"weight";s:1:"0";s:10:"javascript";s:0:"";}';
-    $this->sourceDatabase->update('variable')
-      ->fields(array(
-        'value' => $value
-      ))
-      ->condition('name', 'language_default' )
-      ->execute();
-    $this->executeMigrations(['language', 'd6_default_language']);
-    $default_language = ConfigurableLanguage::load($langcode);
-    $this->assertNotNull($default_language);
-    $this->assertIdentical($langcode, $this->config('system.site')->get('default_langcode'));
-  }
-
-}
diff --git a/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateDefaultLanguageTest.php b/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateDefaultLanguageTest.php
new file mode 100644
index 0000000..4f408e2
--- /dev/null
+++ b/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateDefaultLanguageTest.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Drupal\Tests\language\Kernel\Migrate\d6;
+
+use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
+
+/**
+ * Tests the default language variable migration.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateDefaultLanguageTest extends MigrateDrupal6TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['language'];
+
+  /**
+   * Tests the migration of the language_default variable to the
+   * system.site.default_langcode config key, with an existing language.
+   */
+  public function testMigrationWithExistingLanguage() {
+    $this->doTestMigration('fr');
+  }
+
+  /**
+   * Tests the migration of the language_default variable to the
+   * system.site.default_langcode config key, with a non-existent language.
+   */
+  public function testMigrationWithNonExistentLanguage() {
+    $this->doTestMigration('tv');
+  }
+
+  /**
+   * Helper method to test the migration.
+   */
+  protected function doTestMigration($langcode) {
+    // The default language of the test fixture is English. Change it to
+    // something else before migrating, to be sure that the source site
+    // default language is migrated.
+    $value = 'O:8:"stdClass":11:{s:8:"language";s:2:"' . $langcode . '";s:4:"name";s:6:"French";s:6:"native";s:6:"French";s:9:"direction";s:1:"0";s:7:"enabled";i:1;s:7:"plurals";s:1:"0";s:7:"formula";s:0:"";s:6:"domain";s:0:"";s:6:"prefix";s:0:"";s:6:"weight";s:1:"0";s:10:"javascript";s:0:"";}';
+    $this->sourceDatabase->update('variable')
+      ->fields(array(
+        'value' => $value
+      ))
+      ->condition('name', 'language_default' )
+      ->execute();
+    $this->executeMigrations(['language', 'default_language']);
+    $default_language = ConfigurableLanguage::load($langcode);
+    $this->assertNotNull($default_language);
+    $this->assertIdentical($langcode, $this->config('system.site')->get('default_langcode'));
+  }
+
+}
diff --git a/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateDefaultLanguageTest.php b/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateDefaultLanguageTest.php
new file mode 100644
index 0000000..7867652
--- /dev/null
+++ b/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateDefaultLanguageTest.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Drupal\Tests\language\Kernel\Migrate\d7;
+
+use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\Tests\migrate_drupal\Kernel\d7\MigrateDrupal7TestBase;
+
+/**
+ * Tests the default language variable migration.
+ *
+ * @group migrate_drupal_7
+ */
+class MigrateDefaultLanguageTest extends MigrateDrupal7TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['language'];
+
+  /**
+   * Tests the migration of the language_default variable to the
+   * system.site.default_langcode config key, with an existing language.
+   */
+  public function testMigrationWithExistingLanguage() {
+    $this->doTestMigration('is');
+  }
+
+  /**
+   * Tests the migration of the language_default variable to the
+   * system.site.default_langcode config key, with a non-existent language.
+   */
+  public function testMigrationWithNonExistentLanguage() {
+    $this->doTestMigration('tv');
+  }
+
+  /**
+   * Helper method to test the migration.
+   */
+  protected function doTestMigration($langcode) {
+    // The default language of the test fixture is English. Change it to
+    // something else before migrating, to be sure that the source site
+    // default language is migrated.
+    $value = 'O:8:"stdClass":11:{s:8:"language";s:2:"' . $langcode . '";s:4:"name";s:9:"Icelandic";s:6:"native";s:9:"Icelandic";s:9:"direction";s:1:"0";s:7:"enabled";i:1;s:7:"plurals";s:1:"0";s:7:"formula";s:0:"";s:6:"domain";s:0:"";s:6:"prefix";s:0:"";s:6:"weight";s:1:"0";s:10:"javascript";s:0:"";}';
+    $this->sourceDatabase->update('variable')
+      ->fields(array(
+        'value' => $value
+      ))
+      ->condition('name', 'language_default' )
+      ->execute();
+    $this->executeMigrations(['language', 'default_language']);
+    $default_language = ConfigurableLanguage::load($langcode);
+    $this->assertNotNull($default_language);
+    $this->assertIdentical($langcode, $this->config('system.site')->get('default_langcode'));
+  }
+
+}
diff --git a/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
index f5ffdbf..4c1f4d3 100644
--- a/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
+++ b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
@@ -170,7 +170,7 @@ class MigrateUpgradeForm extends ConfirmFormBase {
       'source_module' => 'dblog',
       'destination_module' => 'dblog',
     ],
-    'd6_default_language' => [
+    'default_language' => [
       'source_module' => 'locale',
       'destination_module' => 'language',
     ],