diff --git a/build/build-preload.php b/build/build-preload.php
index de87adabbbc..9f460325fd3 100755
--- a/build/build-preload.php
+++ b/build/build-preload.php
@@ -61,18 +61,11 @@ final class PreloadBuilder
 // edge case during Rector tests case, happens when
 // 1. phpstan autoload test case is triggered first,
 // 2. all php-parser classes are loaded,
-if (defined('PHPUNIT_COMPOSER_INSTALL') && isPHPStanTestPreloaded()) {
+if (defined('PHPUNIT_COMPOSER_INSTALL')
+    && class_exists(PHPStanTestCase::class, false)
+    && interface_exists(Node::class, false)) {
     return;
 }
-
-function isPHPStanTestPreloaded(): bool
-{
-    if (! class_exists(PHPStanTestCase::class, false)) {
-        return false;
-    }
-
-    return interface_exists(Node::class, false);
-}
 CODE_SAMPLE;
 
     /**
diff --git a/preload-split-package.php b/preload-split-package.php
index da953d5a7e5..6a969d4aad8 100644
--- a/preload-split-package.php
+++ b/preload-split-package.php
@@ -12,19 +12,12 @@
 // edge case during Rector tests case, happens when
 // 1. phpstan autoload test case is triggered first,
 // 2. all php-parser classes are loaded,
-if (defined('PHPUNIT_COMPOSER_INSTALL') && isPHPStanTestPreloaded()) {
+if (defined('PHPUNIT_COMPOSER_INSTALL')
+    && class_exists(PHPStanTestCase::class, false)
+    && interface_exists(Node::class, false)) {
     return;
 }
 
-function isPHPStanTestPreloaded(): bool
-{
-    if (! class_exists(PHPStanTestCase::class, false)) {
-        return false;
-    }
-
-    return interface_exists(Node::class, false);
-}
-
 require_once __DIR__ . '/../../../vendor/nikic/php-parser/lib/PhpParser/Node.php';
 require_once __DIR__ . '/src/Contract/PhpParser/Node/StmtsAwareInterface.php';
 require_once __DIR__ . '/../../../vendor/nikic/php-parser/lib/PhpParser/NodeAbstract.php';
diff --git a/preload.php b/preload.php
index cecb0b90b4c..55beb85fb92 100644
--- a/preload.php
+++ b/preload.php
@@ -12,19 +12,12 @@
 // edge case during Rector tests case, happens when
 // 1. phpstan autoload test case is triggered first,
 // 2. all php-parser classes are loaded,
-if (defined('PHPUNIT_COMPOSER_INSTALL') && isPHPStanTestPreloaded()) {
+if (defined('PHPUNIT_COMPOSER_INSTALL')
+    && class_exists(PHPStanTestCase::class, false)
+    && interface_exists(Node::class, false)) {
     return;
 }
 
-function isPHPStanTestPreloaded(): bool
-{
-    if (! class_exists(PHPStanTestCase::class, false)) {
-        return false;
-    }
-
-    return interface_exists(Node::class, false);
-}
-
 require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/Node.php';
 require_once __DIR__ . '/src/Contract/PhpParser/Node/StmtsAwareInterface.php';
 require_once __DIR__ . '/vendor/nikic/php-parser/lib/PhpParser/NodeAbstract.php';