diff --git a/src/Entity/MobileSession.php b/src/Entity/MobileSession.php
index 70df5a81..831d14fd 100644
--- a/src/Entity/MobileSession.php
+++ b/src/Entity/MobileSession.php
@@ -38,7 +38,7 @@ class MobileSession
 
     // device id or push id used by device
     /**
-     * @ORM\Column(type="string", length=200)
+     * @ORM\Column(type="string", length=200, nullable=true)
      */
     protected $device_push_id;