diff --git a/core/modules/language/migration_templates/d6_default_language.yml b/core/modules/language/migration_templates/d6_default_language.yml
new file mode 100644
index 0000000..7f8821b
--- /dev/null
+++ b/core/modules/language/migration_templates/d6_default_language.yml
@@ -0,0 +1,20 @@
+id: d6_default_language
+label: Default language
+migration_tags:
+  - Drupal 6
+source:
+  plugin: variable
+  variables:
+    - language_default
+process:
+  default_langcode:
+    -
+      plugin: callback
+      callable: get_object_vars
+      source: language_default
+    -
+      plugin: extract
+      source: language
+destination:
+  plugin: config
+  config_name: system.site
diff --git a/core/modules/language/src/Tests/Migrate/d6/MigrateDefaultLanguageTest.php b/core/modules/language/src/Tests/Migrate/d6/MigrateDefaultLanguageTest.php
new file mode 100644
index 0000000..25db77d
--- /dev/null
+++ b/core/modules/language/src/Tests/Migrate/d6/MigrateDefaultLanguageTest.php
@@ -0,0 +1,31 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\language\Tests\Migrate\d6\MigrateDefaultLanguageTest.
+ */
+
+namespace Drupal\language\Tests\Migrate\d6;
+
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
+
+/**
+ * @group migrate_drupal_6
+ */
+class MigrateDefaultLanguageTest extends MigrateDrupal6TestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['language'];
+
+  /**
+   * Tests migration of the language_default variable to the
+   * system.site.default_langcode config key.
+   */
+  public function testMigration() {
+    $this->executeMigration('d6_default_language');
+    $this->assertIdentical('en', $this->config('system.site')->get('default_langcode'));
+  }
+
+}