diff --git a/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
index fdcb26e..c886db2 100644
--- a/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
+++ b/core/modules/migrate_drupal_ui/src/Form/MigrateUpgradeForm.php
@@ -162,6 +162,10 @@ class MigrateUpgradeForm extends ConfirmFormBase {
       'source_module' => 'contact',
       'destination_module' => 'contact',
     ],
+    'd6_default_language' => [
+      'source_module' => 'locale',
+      'destination_module' => 'language',
+    ],
     'd6_dblog_settings' => [
       'source_module' => 'dblog',
       'destination_module' => 'dblog',