diff --git a/src/Symfony/Component/Config/Definition/BaseNode.php b/src/Symfony/Component/Config/Definition/BaseNode.php
index d942b28cc7..b96e2d608b 100644
--- a/src/Symfony/Component/Config/Definition/BaseNode.php
+++ b/src/Symfony/Component/Config/Definition/BaseNode.php
@@ -41,7 +41,7 @@ abstract class BaseNode implements NodeInterface
      */
     public function __construct(?string $name, NodeInterface $parent = null, string $pathSeparator = self::DEFAULT_PATH_SEPARATOR)
     {
-        if (false !== strpos($name = (string) , $pathSeparator)) {
+        if (false !== strpos($name = (string) $name, $pathSeparator)) {
             throw new \InvalidArgumentException('The name must not contain "'.$pathSeparator.'".');
         }