diff --git a/core/modules/language/src/Plugin/migrate/destination/DefaultLangcode.php b/core/modules/language/src/Plugin/migrate/destination/DefaultLangcode.php
index 47c44c0..a5a50a9 100644
--- a/core/modules/language/src/Plugin/migrate/destination/DefaultLangcode.php
+++ b/core/modules/language/src/Plugin/migrate/destination/DefaultLangcode.php
@@ -21,10 +21,11 @@ class DefaultLangcode extends Config {
    */
   public function import(Row $row, array $old_destination_id_values = array()) {
     $destination = $row->getDestination();
+    $langcode = $destination['default_langcode'];
 
     // 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.", $destination['default_langcode']));
+    if (ConfigurableLanguage::load($langcode) === NULL) {
+      throw new MigrateException("The language '$langcode' does not exist on this site.");
     }
 
     $this->config->set('default_langcode', $destination['default_langcode']);
diff --git a/core/modules/language/tests/src/Kernel/Migrate/MigrateDefaultLanguageTrait.php b/core/modules/language/tests/src/Kernel/Migrate/MigrateDefaultLanguageTrait.php
new file mode 100644
index 0000000..deb6020
--- /dev/null
+++ b/core/modules/language/tests/src/Kernel/Migrate/MigrateDefaultLanguageTrait.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Drupal\Tests\language\Kernel\Migrate;
+
+use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\migrate\Plugin\MigrationInterface;
+
+/**
+ * Tests the default language variable migration.
+ */
+trait MigrateDefaultLanguageTrait {
+
+  /**
+   * Helper method to test the migration.
+   *
+   * @param string $langcode
+   *   The langcode of the default language.
+   * @param bool $existing
+   *   Whether the default language exists on the destination.
+   */
+  protected function doTestMigration($langcode, $existing = TRUE) {
+    // 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->startCollectingMessages();
+    $this->executeMigrations(['language', 'default_language']);
+
+    if ($existing) {
+      // If the default language exists, we should be able to load it and the
+      // default_langcode config should be set.
+      $default_language = ConfigurableLanguage::load($langcode);
+      $this->assertNotNull($default_language);
+      $this->assertIdentical($langcode, $this->config('system.site')->get('default_langcode'));
+    }
+    else {
+      // Otherwise, the migration log should contain an error message.
+      $messages = $this->migration->getIdMap()->getMessageIterator();
+      $count = 0;
+      foreach ($messages as $message) {
+        $count++;
+        $this->assertEqual($message->message, "The language '$langcode' does not exist on this site.");
+        $this->assertEqual($message->level, MigrationInterface::MESSAGE_ERROR);
+      }
+      $this->assertEqual($count, 1);
+    }
+  }
+
+}
diff --git a/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateDefaultLanguageTest.php b/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateDefaultLanguageTest.php
index 4f408e2..de2dcfe 100644
--- a/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateDefaultLanguageTest.php
+++ b/core/modules/language/tests/src/Kernel/Migrate/d6/MigrateDefaultLanguageTest.php
@@ -2,7 +2,7 @@
 
 namespace Drupal\Tests\language\Kernel\Migrate\d6;
 
-use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\Tests\language\Kernel\Migrate\MigrateDefaultLanguageTrait;
 use Drupal\Tests\migrate_drupal\Kernel\d6\MigrateDrupal6TestBase;
 
 /**
@@ -12,6 +12,8 @@
  */
 class MigrateDefaultLanguageTest extends MigrateDrupal6TestBase {
 
+  use MigrateDefaultLanguageTrait;
+
   /**
    * {@inheritdoc}
    */
@@ -30,27 +32,7 @@ public function testMigrationWithExistingLanguage() {
    * 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'));
+    $this->doTestMigration('tv', FALSE);
   }
 
 }
diff --git a/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateDefaultLanguageTest.php b/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateDefaultLanguageTest.php
index 7867652..f4b4162 100644
--- a/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateDefaultLanguageTest.php
+++ b/core/modules/language/tests/src/Kernel/Migrate/d7/MigrateDefaultLanguageTest.php
@@ -2,7 +2,7 @@
 
 namespace Drupal\Tests\language\Kernel\Migrate\d7;
 
-use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\Tests\language\Kernel\Migrate\MigrateDefaultLanguageTrait;
 use Drupal\Tests\migrate_drupal\Kernel\d7\MigrateDrupal7TestBase;
 
 /**
@@ -12,6 +12,8 @@
  */
 class MigrateDefaultLanguageTest extends MigrateDrupal7TestBase {
 
+  use MigrateDefaultLanguageTrait;
+
   /**
    * {@inheritdoc}
    */
@@ -30,27 +32,7 @@ public function testMigrationWithExistingLanguage() {
    * 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'));
+    $this->doTestMigration('tv', FALSE);
   }
 
 }