diff --git a/src/Bundle/ChillCalendarBundle/Entity/Calendar.php b/src/Bundle/ChillCalendarBundle/Entity/Calendar.php
index da0f797d7..ba5ef4a6d 100644
--- a/src/Bundle/ChillCalendarBundle/Entity/Calendar.php
+++ b/src/Bundle/ChillCalendarBundle/Entity/Calendar.php
@@ -37,7 +37,7 @@ class Calendar
      * @ORM\GeneratedValue
      * @ORM\Column(type="integer")
      */
-    private $id;
+    private ?int $id;
 
     /**
      * @ORM\ManyToOne(targetEntity="Chill\MainBundle\Entity\User")