diff --git a/app/Events/UserMerged.php b/app/Events/UserMerged.php
index b045fdef03..3a7f4d6a2c 100644
--- a/app/Events/UserMerged.php
+++ b/app/Events/UserMerged.php
@@ -15,7 +15,7 @@ class UserMerged
      *
      * @return void
      */
-    public function __construct(User $from_user, User $to_user, User $admin)
+    public function __construct(User $from_user, User $to_user, ?User $admin)
     {
         $this->merged_from        = $from_user;
         $this->merged_to      = $to_user;