diff --git a/src/Domain/Model/Traits/DomainEventTrait.php b/src/Domain/Model/Traits/DomainEventTrait.php
index 7762e54..7a04b24 100644
--- a/src/Domain/Model/Traits/DomainEventTrait.php
+++ b/src/Domain/Model/Traits/DomainEventTrait.php
@@ -21,7 +21,7 @@ trait DomainEventTrait
      */
     private string $occurredOn;
 
-    private string|null $actorId;
+    private string|null $actorId = null;
 
     public function setActorId(?string $actorId): void
     {