diff --git a/app/services/post_alerter.rb b/app/services/post_alerter.rb
index 83ae94e17a9..edd0deb69bd 100644
--- a/app/services/post_alerter.rb
+++ b/app/services/post_alerter.rb
@@ -146,8 +146,15 @@ class PostAlerter
     # replies
     reply_to_user = post.reply_notification_target
 
-    if new_record && reply_to_user && !notified.include?(reply_to_user) && notify_about_reply?(post)
-      notified += notify_non_pm_users(reply_to_user, :replied, post)
+    if new_record
+      if reply_to_user && !notified.include?(reply_to_user) && notify_about_reply?(post)
+        notified += notify_non_pm_users(reply_to_user, :replied, post)
+      end
+
+      topic_author = post.topic.user
+      if topic_author && !notified.include?(topic_author) && user_watching_topic?(topic_author, post.topic)
+        notified += notify_non_pm_users(topic_author, :replied, post)
+      end
     end
 
     DiscourseEvent.trigger(:post_alerter_before_quotes, post, new_record, notified)
@@ -885,4 +892,12 @@ class PostAlerter
   def is_replying?(user, reply_to_user, quoted_users)
     reply_to_user == user || quoted_users.include?(user)
   end
+
+  def user_watching_topic?(user, topic)
+    TopicUser.exists?(
+      user_id: user.id,
+      topic_id: topic.id,
+      notification_level: TopicUser.notification_levels[:watching]
+    )
+  end
 end
diff --git a/spec/services/post_alerter_spec.rb b/spec/services/post_alerter_spec.rb
index 67d1508ce22..4dac502dd8e 100644
--- a/spec/services/post_alerter_spec.rb
+++ b/spec/services/post_alerter_spec.rb
@@ -1322,6 +1322,27 @@ RSpec.describe PostAlerter do
       NotificationEmailer.expects(:process_notification).once
       expect { PostAlerter.post_created(reply) }.to change(user.notifications, :count).by(1)
     end
+
+    it "creates a notification of type `replied` instead of `posted` for the topic author if they're watching the topic" do
+      Jobs.run_immediately!
+
+      u1 = Fabricate(:admin)
+      u2 = Fabricate(:admin)
+
+      topic = create_topic(user: u1)
+
+      u1.notifications.destroy_all
+
+      expect do
+        create_post(topic: topic, user: u2)
+      end.to change { u1.reload.notifications.count }.by(1)
+      expect(u1.notifications.exists?(
+        topic_id: topic.id,
+        notification_type: Notification.types[:replied],
+        post_number: 1,
+        read: false
+      )).to eq(true)
+    end
   end
 
   context "with category" do