diff --git a/app/assets/javascripts/discourse/controllers/discovery/topics.js.es6 b/app/assets/javascripts/discourse/controllers/discovery/topics.js.es6
index a58dccc90a5..bc2794173f1 100644
--- a/app/assets/javascripts/discourse/controllers/discovery/topics.js.es6
+++ b/app/assets/javascripts/discourse/controllers/discovery/topics.js.es6
@@ -85,8 +85,7 @@ var controllerOpts = {
       if (selected.length > 0) {
         promise = Discourse.Topic.bulkOperation(selected, operation);
       } else {
-        var category = this.get('category');
-        promise = Discourse.Topic.bulkOperationByFilter('unread', operation, category ? category.id : null);
+        promise = Discourse.Topic.bulkOperationByFilter('unread', operation, this.get('category.id'));
       }
       promise.then(function(result) {
         if (result && result.topic_ids) {
diff --git a/app/assets/javascripts/discourse/models/topic.js b/app/assets/javascripts/discourse/models/topic.js
index e0ddb17553d..0b876a96d5d 100644
--- a/app/assets/javascripts/discourse/models/topic.js
+++ b/app/assets/javascripts/discourse/models/topic.js
@@ -454,7 +454,7 @@ Discourse.Topic.reopenClass({
 
   bulkOperationByFilter: function(filter, operation, categoryId) {
     var data = { filter: filter, operation: operation };
-    if (categoryId) data['categoryId'] = categoryId;
+    if (categoryId) data['category_id'] = categoryId;
     return Discourse.ajax("/topics/bulk", {
       type: 'PUT',
       data: data
diff --git a/app/controllers/topics_controller.rb b/app/controllers/topics_controller.rb
index 6cf0501c5f0..ee03c40d742 100644
--- a/app/controllers/topics_controller.rb
+++ b/app/controllers/topics_controller.rb
@@ -359,8 +359,8 @@ class TopicsController < ApplicationController
       topic_ids = params[:topic_ids].map {|t| t.to_i}
     elsif params[:filter] == 'unread'
       tq = TopicQuery.new(current_user)
-      if params[:categoryId]
-        topic_ids = TopicQuery.unread_filter(tq.joined_topic_user).listable_topics.where('category_id = ?', params[:categoryId]).pluck(:id)
+      if params[:category_id]
+        topic_ids = TopicQuery.unread_filter(tq.joined_topic_user).listable_topics.where('category_id = ?', params[:category_id]).pluck(:id)
       else
         topic_ids = TopicQuery.unread_filter(tq.joined_topic_user).listable_topics.pluck(:id)
       end