diff --git a/app/Models/ConsumableAssignment.php b/app/Models/ConsumableAssignment.php
index ae84cd19dc..db0cfa4bd6 100644
--- a/app/Models/ConsumableAssignment.php
+++ b/app/Models/ConsumableAssignment.php
@@ -13,7 +13,7 @@ class ConsumableAssignment extends Model
     protected $table = 'consumables_users';
 
     public $rules = [
-        'assigned_to'        => 'exists:users,id',
+        'assigned_to'        => 'required|exists:users,id',
     ];
 
     public function consumable()