diff --git a/extensions/subscriptions/src/Listeners/PersistSubscriptionData.php b/extensions/subscriptions/src/Listeners/PersistSubscriptionData.php
index 69c247017..e29075528 100755
--- a/extensions/subscriptions/src/Listeners/PersistSubscriptionData.php
+++ b/extensions/subscriptions/src/Listeners/PersistSubscriptionData.php
@@ -1,6 +1,7 @@
 <?php namespace Flarum\Subscriptions\Listeners;
 
 use Flarum\Events\DiscussionWillBeSaved;
+use Flarum\Core\Exceptions\PermissionDeniedException;
 
 class PersistSubscriptionData
 {
@@ -18,6 +19,10 @@ class PersistSubscriptionData
             $actor = $event->actor;
             $subscription = $data['attributes']['subscription'];
 
+            if (! $actor->exists) {
+                throw new PermissionDeniedException;
+            }
+
             $state = $discussion->stateFor($actor);
 
             if (! in_array($subscription, ['follow', 'ignore'])) {