diff --git a/core/includes/update.inc b/core/includes/update.inc
index f711507..c6ad929 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -218,8 +218,8 @@ function update_prepare_d8_language() {
         unset($language_default->language);
       }
       unset($language_default->enabled);
-      variable_set('language_default', $language_default);
     }
+    variable_set('language_default', (array) $language_default);
   }
 }
 
diff --git a/core/lib/Drupal/Core/Language/Language.php b/core/lib/Drupal/Core/Language/Language.php
index 3edb07d..b1d35f9 100644
--- a/core/lib/Drupal/Core/Language/Language.php
+++ b/core/lib/Drupal/Core/Language/Language.php
@@ -50,4 +50,16 @@ class Language {
       $this->$var = $value;
     }
   }
+
+  /**
+   * Returns an array with some of the attributes of the class.
+   */
+  public function toArray() {
+    $attributes = array('name', 'langcode', 'direction', 'enabled', 'weight', 'default');
+    $return = array();
+    foreach ($attributes as $attribute) {
+      $return[$attribute] = $this->{$attribute};
+    }
+    return $return;
+  }
 }
diff --git a/core/modules/language/language.module b/core/modules/language/language.module
index 7acc783..c8162c8 100644
--- a/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -184,7 +184,7 @@ function language_save($language) {
   if (!empty($language->default)) {
     // Set the new version of this language as default in a variable.
     $default_language = language_default();
-    variable_set('language_default', $language);
+    variable_set('language_default', (array) $language);
   }
 
   // Update language count based on enabled language count.
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageDependencyInjectionTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageDependencyInjectionTest.php
index 39209f5..267a6ab 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageDependencyInjectionTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageDependencyInjectionTest.php
@@ -72,7 +72,7 @@ class LanguageDependencyInjectionTest extends WebTestBase {
    */
   function testDependencyInjectedNewDefaultLanguage() {
     // Change the language default object to different values.
-    $new_language_default = (object) array(
+    $new_language_default = array(
       'langcode' => 'fr',
       'name' => 'French',
       'direction' => 0,
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
index 3495548..cba4c13 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageUILanguageNegotiationTest.php
@@ -93,7 +93,7 @@ class LanguageUILanguageNegotiationTest extends WebTestBase {
     // be some bug.
     drupal_static_reset('language_list');
     $languages = language_list();
-    variable_set('language_default', $languages['vi']);
+    variable_set('language_default', $languages['vi']->toArray());
     // First visit this page to make sure our target string is searchable.
     $this->drupalGet('admin/config');
     // Now the t()'ed string is in db so switch the language back to default.