diff --git a/app/assets/javascripts/discourse/controllers/topic.js.es6 b/app/assets/javascripts/discourse/controllers/topic.js.es6
index 0a56160bb..f3ab828c1 100644
--- a/app/assets/javascripts/discourse/controllers/topic.js.es6
+++ b/app/assets/javascripts/discourse/controllers/topic.js.es6
@@ -865,7 +865,7 @@ export default Ember.Controller.extend(SelectedPostsCount, BufferedContent, {
         }
       });
 
-      if (highestReadPostId > 0) {
+      if (highestReadPostId > 0 && highestReadPostId > (topic.get('last_read_post_id') || 0)) {
         topic.set('last_read_post_id', highestReadPostId);
       }
 
diff --git a/app/assets/javascripts/discourse/widgets/topic-timeline.js.es6 b/app/assets/javascripts/discourse/widgets/topic-timeline.js.es6
index 851de634e..d881c8d93 100644
--- a/app/assets/javascripts/discourse/widgets/topic-timeline.js.es6
+++ b/app/assets/javascripts/discourse/widgets/topic-timeline.js.es6
@@ -120,7 +120,7 @@ createWidget('timeline-scrollarea', {
 
     if (lastReadId && lastReadNumber) {
       const idx = postStream.get('stream').indexOf(lastReadId) + 1;
-      result.lastRead = lastReadNumber;
+      result.lastRead = idx;
       result.lastReadPercentage = this._percentFor(topic, idx);
     }