diff --git a/src/Symfony/Component/Config/Resource/ReflectionClassResource.php b/src/Symfony/Component/Config/Resource/ReflectionClassResource.php
index a0aeb354c74ff..051158b2413f3 100644
--- a/src/Symfony/Component/Config/Resource/ReflectionClassResource.php
+++ b/src/Symfony/Component/Config/Resource/ReflectionClassResource.php
@@ -161,6 +161,8 @@ private function generateSignature(\ReflectionClass $class): iterable
             }
         }
 
+        $defined = \Closure::bind(static function ($c) { return \defined($c); }, null, $class->name);
+
         foreach ($class->getMethods(\ReflectionMethod::IS_PUBLIC | \ReflectionMethod::IS_PROTECTED) as $m) {
             if (\PHP_VERSION_ID >= 80000) {
                 foreach ($m->getAttributes() as $a) {
@@ -187,7 +189,7 @@ private function generateSignature(\ReflectionClass $class): iterable
                     continue;
                 }
 
-                if (!$p->isDefaultValueConstant() || \defined($p->getDefaultValueConstantName())) {
+                if (!$p->isDefaultValueConstant() || $defined($p->getDefaultValueConstantName())) {
                     $defaults[$p->name] = $p->getDefaultValue();
 
                     continue;
diff --git a/src/Symfony/Component/Config/Tests/Resource/ReflectionClassResourceTest.php b/src/Symfony/Component/Config/Tests/Resource/ReflectionClassResourceTest.php
index 4f61c5bbd7c61..8ba3a8c2c93cf 100644
--- a/src/Symfony/Component/Config/Tests/Resource/ReflectionClassResourceTest.php
+++ b/src/Symfony/Component/Config/Tests/Resource/ReflectionClassResourceTest.php
@@ -164,6 +164,7 @@ public function provideHashedSignature(): iterable
 
         yield [true, 17, 'public function ccc($bar = 187) {}'];
         yield [true, 17, 'public function ccc($bar = ANOTHER_ONE_THAT_WILL_NEVER_BE_DEFINED_CCCCCCCCC) {}'];
+        yield [true, 17, 'public function ccc($bar = parent::BOOM) {}'];
         yield [true, 17, null, static function () { \define('A_CONSTANT_THAT_FOR_SURE_WILL_NEVER_BE_DEFINED_CCCCCC', 'foo'); }];
     }