diff --git a/src/Discussion/Discussion.php b/src/Discussion/Discussion.php
index 1b1bfc194..e73be2dad 100644
--- a/src/Discussion/Discussion.php
+++ b/src/Discussion/Discussion.php
@@ -380,7 +380,7 @@ class Discussion extends AbstractModel
      */
     public function lastUser()
     {
-        return $this->belongsTo(User::class, 'last_user_id');
+        return $this->belongsTo(User::class, 'last_posted_user_id');
     }
 
     /**
diff --git a/src/Notification/NotificationRepository.php b/src/Notification/NotificationRepository.php
index 57ed3b02a..629fe8792 100644
--- a/src/Notification/NotificationRepository.php
+++ b/src/Notification/NotificationRepository.php
@@ -34,7 +34,7 @@ class NotificationRepository
             ->whereIn('type', $user->getAlertableNotificationTypes())
             ->whereNull('deleted_at')
             ->groupBy('type', 'subject_id')
-            ->orderByRaw('MAX(time) DESC')
+            ->orderByRaw('MAX(created_at) DESC')
             ->skip($offset)
             ->take($limit);
 
diff --git a/src/Post/PostRepository.php b/src/Post/PostRepository.php
index 8213be5e8..f6ed861c5 100644
--- a/src/Post/PostRepository.php
+++ b/src/Post/PostRepository.php
@@ -136,8 +136,8 @@ class PostRepository
         $query = Discussion::find($discussionId)
             ->posts()
             ->whereVisibleTo($actor)
-            ->where('time', '<', function ($query) use ($discussionId, $number) {
-                $query->select('time')
+            ->where('created_at', '<', function ($query) use ($discussionId, $number) {
+                $query->select('created_at')
                       ->from('posts')
                       ->where('discussion_id', $discussionId)
                       ->whereNotNull('number')