diff --git a/core/tests/Drupal/Tests/ComposerIntegrationTest.php b/core/tests/Drupal/Tests/ComposerIntegrationTest.php
index 511fd529caba..b56849d86313 100644
--- a/core/tests/Drupal/Tests/ComposerIntegrationTest.php
+++ b/core/tests/Drupal/Tests/ComposerIntegrationTest.php
@@ -47,6 +47,7 @@ class ComposerIntegrationTest extends UnitTestCase {
       $this->root . '/core/lib/Drupal/Component/Annotation',
       $this->root . '/core/lib/Drupal/Component/Assertion',
       $this->root . '/core/lib/Drupal/Component/Bridge',
+      $this->root . '/core/lib/Drupal/Component/ClassFinder',
       $this->root . '/core/lib/Drupal/Component/Datetime',
       $this->root . '/core/lib/Drupal/Component/DependencyInjection',
       $this->root . '/core/lib/Drupal/Component/Diff',