diff --git a/src/Framework/TestSuite.php b/src/Framework/TestSuite.php
index d1ab801afad..0bb81844b1b 100644
--- a/src/Framework/TestSuite.php
+++ b/src/Framework/TestSuite.php
@@ -389,7 +389,7 @@ public function addTestFile(string $filename): void
         if (is_file($filename) && substr($filename, -5) === '.phpt') {
             $this->addTest(new PhptTestCase($filename));
 
-            $this->declaredClasses = get_declared_classes();
+            $this->declaredClassesPointer = count(get_declared_classes());
 
             return;
         }