diff --git a/core/modules/migrate_drupal/tests/modules/migrate_field_plugin_manager_test/src/Plugin/migrate/cckfield/D6FileField.php b/core/modules/migrate_drupal/tests/modules/migrate_field_plugin_manager_test/src/Plugin/migrate/cckfield/D6FileField.php
new file mode 100644
index 0000000..cf06b87
--- /dev/null
+++ b/core/modules/migrate_drupal/tests/modules/migrate_field_plugin_manager_test/src/Plugin/migrate/cckfield/D6FileField.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace Drupal\migrate_field_plugin_manager_test\Plugin\migrate\cckfield;
+
+use Drupal\migrate\Plugin\MigrationInterface;
+use Drupal\migrate_drupal\Plugin\migrate\cckfield\CckFieldPluginBase;
+
+/**
+ * @MigrateCckField(
+ *   id = "filefield",
+ *   core = {6}
+ * )
+ */
+class D6FileField extends CckFieldPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFieldFormatterMap() {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processCckFieldValues(MigrationInterface $migration, $field_name, $data) {
+    // Don't need to do anything here.
+  }
+
+}
diff --git a/core/modules/migrate_drupal/tests/src/Kernel/MigrateFieldPluginManagerTest.php b/core/modules/migrate_drupal/tests/src/Kernel/MigrateFieldPluginManagerTest.php
index 69bef4e..6e6c0d0 100644
--- a/core/modules/migrate_drupal/tests/src/Kernel/MigrateFieldPluginManagerTest.php
+++ b/core/modules/migrate_drupal/tests/src/Kernel/MigrateFieldPluginManagerTest.php
@@ -3,6 +3,7 @@
 namespace Drupal\Tests\migrate_drupal\Kernel;
 
 use Drupal\Component\Plugin\Exception\PluginNotFoundException;
+use Drupal\migrate_field_plugin_manager_test\Plugin\migrate\cckfield\D6FileField;
 
 /**
  * Tests the field plugin manager.
@@ -56,4 +57,22 @@ public function testPluginSelection() {
     }
   }
 
+  /**
+   * Tests the cckfield backwards compatibility layer.
+   */
+  public function testCckfieldBackwardsCompatibility() {
+    $plugin_manager = $this->container->get('plugin.manager.migrate.cckfield');
+
+    $configuration = ['core' => 6];
+    $plugin_id = $plugin_manager->getPluginIdFromFieldType('filefield', $configuration);
+    $plugin = $plugin_manager->createInstance($plugin_id, $configuration);
+
+    $this->assertInstanceOf(D6FileField::class, $plugin, 'cckfield plugin for D6 filefield exists');
+
+    // Ensure that the processCckFieldValues() method exists and is callable
+    // (i.e., public).
+    $callable = [$plugin, 'processCckFieldValues'];
+    $this->assertInternalType('callable', $callable, 'processCckFieldValues method is callable');
+  }
+
 }