diff --git a/src/Doctrine/EntityRelation.php b/src/Doctrine/EntityRelation.php
index 91db3effc..abb35aa36 100644
--- a/src/Doctrine/EntityRelation.php
+++ b/src/Doctrine/EntityRelation.php
@@ -27,7 +27,7 @@ final class EntityRelation
     private bool $isSelfReferencing = false;
     private bool $orphanRemoval = false;
     private bool $mapInverseRelation = true;
-    private ?string $joinTableName = null;
+    private $joinTableName;
 
     public function __construct(
         private string $type,