diff --git a/core/modules/migrate_drupal/tests/fixtures/drupal6.php b/core/modules/migrate_drupal/tests/fixtures/drupal6.php
index 9debae0..b18a4b3 100644
--- a/core/modules/migrate_drupal/tests/fixtures/drupal6.php
+++ b/core/modules/migrate_drupal/tests/fixtures/drupal6.php
@@ -41378,6 +41378,40 @@
   'tnid' => '10',
   'translate' => '0',
 ))
+->values(array(
+  'nid' => '12',
+  'vid' => '15',
+  'type' => 'page',
+  'language' => 'zu',
+  'title' => 'Abantu zulu',
+  'uid' => '1',
+  'status' => '1',
+  'created' => '1444238800',
+  'changed' => '1444238808',
+  'comment' => '0',
+  'promote' => '0',
+  'moderate' => '0',
+  'sticky' => '0',
+  'tnid' => '12',
+  'translate' => '0',
+))
+->values(array(
+  'nid' => '13',
+  'vid' => '16',
+  'type' => 'page',
+  'language' => 'en',
+  'title' => 'The Zulu People',
+  'uid' => '1',
+  'status' => '1',
+  'created' => '1444239050',
+  'changed' => '1444239050',
+  'comment' => '0',
+  'promote' => '0',
+  'moderate' => '0',
+  'sticky' => '0',
+  'tnid' => '12',
+  'translate' => '0',
+))
 ->execute();
 
 $connection->schema()->createTable('node_access', array(
@@ -41807,6 +41841,28 @@
   'timestamp' => '1444239050',
   'format' => '1',
 ))
+->values(array(
+  'nid' => '12',
+  'vid' => '15',
+  'uid' => '1',
+  'title' => 'Abantu zulu',
+  'body' => "Mr. Crusher, ready a collision course with the Borg ship.",
+  'teaser' => "Mr. Crusher, ready a collision course with the Borg ship.",
+  'log' => '',
+  'timestamp' => '1444238808',
+  'format' => '1',
+))
+->values(array(
+  'nid' => '13',
+  'vid' => '16',
+  'uid' => '1',
+  'title' => 'The Zulu People',
+  'body' => 'Mr. Crusher, ready a collision course with the Borg ship.',
+  'teaser' => 'Mr. Crusher, ready a collision course with the Borg ship.',
+  'log' => '',
+  'timestamp' => '1444239050',
+  'format' => '1',
+))
 ->execute();
 
 $connection->schema()->createTable('node_type', array(
diff --git a/core/modules/node/src/Plugin/migrate/source/d6/Node.php b/core/modules/node/src/Plugin/migrate/source/d6/Node.php
index f849bef..2e4d1a6 100644
--- a/core/modules/node/src/Plugin/migrate/source/d6/Node.php
+++ b/core/modules/node/src/Plugin/migrate/source/d6/Node.php
@@ -3,8 +3,13 @@
 namespace Drupal\node\Plugin\migrate\source\d6;
 
 use Drupal\Core\Database\Query\SelectInterface;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Extension\ModuleHandler;
+use Drupal\Core\State\StateInterface;
+use Drupal\migrate\Plugin\MigrationInterface;
 use Drupal\migrate\Row;
 use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Drupal 6 node source from database.
@@ -35,12 +40,41 @@ class Node extends DrupalSqlBase {
   protected $fieldInfo;
 
   /**
+   * The module handler.
+   *
+   * @var \Drupal\Core\Extension\ModuleHandler
+   */
+  protected $moduleHandler;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, StateInterface $state, EntityManagerInterface $entity_manager, ModuleHandler $module_handler) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $state, $entity_manager);
+    $this->moduleHandler = $module_handler;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      $container->get('state'),
+      $container->get('entity.manager'),
+      $container->get('module_handler')
+    );
+  }
+
+  /**
    * {@inheritdoc}
    */
   public function query() {
     $query = $this->select('node_revisions', 'nr');
     $query->innerJoin('node', 'n', static::JOIN);
-    $query->leftJoin('node', 'nt', 'n.tnid = nt.nid');
     $this->handleTranslations($query);
 
     $query->fields('n', array(
@@ -68,7 +102,13 @@ public function query() {
       ));
     $query->addField('n', 'uid', 'node_uid');
     $query->addField('nr', 'uid', 'revision_uid');
-    $query->addField('nt', 'language', 'source_langcode');
+
+    // If the content_translation module is enabled, get the source langcode
+    // to fill the content_translation_source field.
+    if ($this->moduleHandler->moduleExists('content_translation')) {
+      $query->leftJoin('node', 'nt', 'n.tnid = nt.nid');
+      $query->addField('nt', 'language', 'source_langcode');
+    }
 
     if (isset($this->configuration['node_type'])) {
       $query->condition('n.type', $this->configuration['node_type']);
diff --git a/core/modules/node/tests/src/Kernel/Migrate/d6/MigrateNodeTest.php b/core/modules/node/tests/src/Kernel/Migrate/d6/MigrateNodeTest.php
index 97f41fe..7a0a272 100644
--- a/core/modules/node/tests/src/Kernel/Migrate/d6/MigrateNodeTest.php
+++ b/core/modules/node/tests/src/Kernel/Migrate/d6/MigrateNodeTest.php
@@ -105,6 +105,10 @@ public function testNode() {
     $manager = $this->container->get('content_translation.manager');
     $this->assertIdentical('en', $manager->getTranslationMetadata($node->getTranslation('fr'))->getSource());
 
+    // Test that content_translation_source for a source other than English.
+    $node = Node::load(12);
+    $this->assertIdentical('zu', $manager->getTranslationMetadata($node->getTranslation('en'))->getSource());
+
     // Node 11 is a translation of node 10, and should not be imported separately.
     $this->assertNull(Node::load(11), "Node 11 doesn't exist in D8, it was a translation");