diff --git a/core/tests/Drupal/Tests/TestSuites/TestSuiteBaseTest.php b/core/tests/Drupal/Tests/TestSuites/TestSuiteBaseTest.php
index bebb431..0ba8143 100644
--- a/core/tests/Drupal/Tests/TestSuites/TestSuiteBaseTest.php
+++ b/core/tests/Drupal/Tests/TestSuites/TestSuiteBaseTest.php
@@ -4,6 +4,10 @@
 
 use org\bovigo\vfs\vfsStream;
 
+// The test suite class is not part of the autoloader, we need to include it
+// manually.
+require_once __DIR__ . '/../../../TestSuites/TestSuiteBase.php';
+
 /**
  * @coversDefaultClass \Drupal\Tests\TestSuites\TestSuiteBase
  *