diff --git a/app/models/forum_topic.rb b/app/models/forum_topic.rb
index 4183bb32a..4a4acf150 100644
--- a/app/models/forum_topic.rb
+++ b/app/models/forum_topic.rb
@@ -128,9 +128,25 @@ class ForumTopic < ActiveRecord::Base
       ids = result.scan(/\S+/)
       result = ids[(ids.size / 2)..-1].join(" ")
     end
+    update_last_forum_read_at(hash.keys)
     result
   end
 
+  def update_last_forum_read_at(read_forum_topic_ids)
+    query = ForumTopic.scoped
+    if CurrentUser.user.last_forum_read_at.present?
+      query = query.where("updated_at > ?", CurrentUser.last_forum_read_at)
+    end
+    if read_forum_topic_ids.any?
+      query = query.where("id not in (?)", read_forum_topic_ids)
+    end
+    query = query.order("updated_at asc")
+    topic = query.first
+    if topic
+      CurrentUser.user.update_attribute(:last_forum_read_at, topic.updated_at)
+    end
+  end
+
   def merge(topic)
     ForumPost.update_all({:topic_id => id}, :id => topic.posts.map(&:id))
     update_attribute(:is_deleted, true)
diff --git a/test/unit/forum_topic_test.rb b/test/unit/forum_topic_test.rb
index a5a1dd8e7..d549f1928 100644
--- a/test/unit/forum_topic_test.rb
+++ b/test/unit/forum_topic_test.rb
@@ -14,6 +14,45 @@ class ForumTopicTest < ActiveSupport::TestCase
       CurrentUser.ip_addr = nil
     end
 
+    context "#update_last_forum_read_at" do
+      setup do
+        @topics = [@topic]
+        1.upto(6) do |i|
+          Timecop.travel(i.days.from_now) do
+            @topics << FactoryGirl.create(:forum_topic, :title => "xxx")
+          end
+        end
+        @read_forum_topic_ids = []
+        @read_forum_topic_ids << @topics[0]
+        @read_forum_topic_ids << @topics[2]
+        @read_forum_topic_ids << @topics[4]
+      end
+
+      context "when the user's last_forum_read_at is null" do
+        setup do
+          @user.update_attribute(:last_forum_read_at, nil)
+        end
+
+        should "return the oldest unread topic" do
+          @topic.update_last_forum_read_at(@read_forum_topic_ids)
+          @user.reload
+          assert_equal(@topics[1].updated_at.to_i, @user.last_forum_read_at.to_i)
+        end
+      end
+
+      context "when the user's last_forum_read_at is 2 days from now" do
+        setup do
+          @user.update_attribute(:last_forum_read_at, 2.days.from_now)
+        end
+
+        should "return the oldest unread topic" do
+          @topic.update_last_forum_read_at(@read_forum_topic_ids)
+          @user.reload
+          assert_equal(@topics[3].updated_at.to_i, @user.last_forum_read_at.to_i)
+        end
+      end
+    end
+
     context "#merge" do
       setup do
         @topic2 = FactoryGirl.create(:forum_topic, :title => "yyy")