diff --git a/extensions/mentions/js/src/forum/addMentionedByList.js b/extensions/mentions/js/src/forum/addMentionedByList.js
index 45b54023d..48fe082f6 100644
--- a/extensions/mentions/js/src/forum/addMentionedByList.js
+++ b/extensions/mentions/js/src/forum/addMentionedByList.js
@@ -118,7 +118,7 @@ export default function addMentionedByList() {
         });
 
       const limit = 4;
-      const overLimit = repliers.length > limit;
+      const overLimit = post.mentionedByCount() > limit;
 
       // Create a list of unique users who have replied. So even if a user has
       // replied twice, they will only be in this array once.
@@ -136,7 +136,7 @@ export default function addMentionedByList() {
       // others" name to the end of the list. Clicking on it will display a modal
       // with a full list of names.
       if (overLimit) {
-        const count = repliers.length - names.length;
+        const count = post.mentionedByCount() - names.length;
 
         names.push(app.translator.trans('flarum-mentions.forum.post.others_text', { count }));
       }
diff --git a/extensions/mentions/src/Api/LoadMentionedByRelationship.php b/extensions/mentions/src/Api/LoadMentionedByRelationship.php
index 209e3be6b..14fc82430 100644
--- a/extensions/mentions/src/Api/LoadMentionedByRelationship.php
+++ b/extensions/mentions/src/Api/LoadMentionedByRelationship.php
@@ -50,6 +50,16 @@ class LoadMentionedByRelationship
             $loadable = $data->newCollection($data->posts)->filter(function ($post) {
                 return $post instanceof Post;
             });
+
+            // firstPost and lastPost might have been included in the API response,
+            // so we have to make sure counts are also loaded for them.
+            if ($data->firstPost) {
+                $loadable->push($data->firstPost);
+            }
+
+            if ($data->lastPost) {
+                $loadable->push($data->lastPost);
+            }
         } elseif ($data instanceof Collection) {
             $loadable = $data;
         } elseif ($data instanceof Post) {