diff --git a/core/modules/simpletest/src/TestBase.php b/core/modules/simpletest/src/TestBase.php
index 14d7909..2d23f6b 100644
--- a/core/modules/simpletest/src/TestBase.php
+++ b/core/modules/simpletest/src/TestBase.php
@@ -945,6 +945,7 @@ public function run(array $methods = array()) {
 
       try {
         $this->setUp();
+        gc_collect_cycles();
       }
       catch (\Exception $e) {
         $this->exceptionHandler($e);