diff --git a/Gemfile b/Gemfile
index 92c81e10b..f7eca2464 100644
--- a/Gemfile
+++ b/Gemfile
@@ -120,6 +120,7 @@ group :test, :development do
   gem 'simplecov', require: false
   gem 'timecop'
   gem 'rspec-given'
+  gem 'rspec-html-matchers'
   gem 'pry-nav'
   gem 'spork-rails'
   gem 'byebug', require: ENV['RM_INFO'].nil?
diff --git a/Gemfile.lock b/Gemfile.lock
index 8142f566d..5da7f0bc5 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -337,6 +337,9 @@ GEM
     rspec-given (3.5.4)
       given_core (= 3.5.4)
       rspec (>= 2.12)
+    rspec-html-matchers (0.7.0)
+      nokogiri (~> 1)
+      rspec (~> 3)
     rspec-logsplit (0.1.3)
     rspec-mocks (3.2.1)
       diff-lcs (>= 1.2.0, < 2.0)
@@ -511,6 +514,7 @@ DEPENDENCIES
   rmmseg-cpp
   rspec (~> 3.2.0)
   rspec-given
+  rspec-html-matchers
   rspec-rails
   rtlit
   ruby-readability
diff --git a/app/assets/javascripts/admin/templates/embedding.hbs b/app/assets/javascripts/admin/templates/embedding.hbs
index 30f279105..6fbe31c12 100644
--- a/app/assets/javascripts/admin/templates/embedding.hbs
+++ b/app/assets/javascripts/admin/templates/embedding.hbs
@@ -53,6 +53,10 @@
     {{embedding-setting field="embed_blacklist_selector"
                         value=embedding.embed_blacklist_selector
                         placeholder=".ad-unit, header"}}
+
+    {{embedding-setting field="embed_classname_whitelist"
+                        value=embedding.embed_classname_whitelist
+                        placeholder="emoji, classname"}}
   </div>
 
   <div class='embedding-secondary'>
diff --git a/app/models/embedding.rb b/app/models/embedding.rb
index c6081b189..796f80671 100644
--- a/app/models/embedding.rb
+++ b/app/models/embedding.rb
@@ -9,6 +9,7 @@ class Embedding < OpenStruct
        embed_truncate
        embed_whitelist_selector
        embed_blacklist_selector
+       embed_classname_whitelist
        feed_polling_enabled
        feed_polling_url
        embed_username_key_from_feed)
diff --git a/app/models/topic_embed.rb b/app/models/topic_embed.rb
index 8d8485232..317fb230b 100644
--- a/app/models/topic_embed.rb
+++ b/app/models/topic_embed.rb
@@ -69,12 +69,13 @@ class TopicEmbed < ActiveRecord::Base
     original_uri = URI.parse(url)
     opts = {
       tags: %w[div p code pre h1 h2 h3 b em i strong a img ul li ol blockquote],
-      attributes: %w[href src],
+      attributes: %w[href src class],
       remove_empty_nodes: false
     }
 
     opts[:whitelist] = SiteSetting.embed_whitelist_selector if SiteSetting.embed_whitelist_selector.present?
     opts[:blacklist] = SiteSetting.embed_blacklist_selector if SiteSetting.embed_blacklist_selector.present?
+    embed_classname_whitelist = SiteSetting.embed_classname_whitelist if SiteSetting.embed_classname_whitelist.present?
 
     doc = Readability::Document.new(open(url).read, opts)
 
@@ -96,6 +97,16 @@ class TopicEmbed < ActiveRecord::Base
           # If there is a mistyped URL, just do nothing
         end
       end
+      # only allow classes in the whitelist
+      allowed_classes = if embed_classname_whitelist.blank? then [] else embed_classname_whitelist.split(/[ ,]+/i) end
+      doc.search('[class]:not([class=""])').each do |node|
+        classes = node[:class].split(' ').select{ |classname| allowed_classes.include?(classname) }
+        if classes.length === 0
+          node.delete('class')
+        else
+          node[:class] = classes.join(' ')
+        end
+      end
     end
 
     [title, doc.to_html]
diff --git a/config/site_settings.yml b/config/site_settings.yml
index 149713872..a9e80a93a 100644
--- a/config/site_settings.yml
+++ b/config/site_settings.yml
@@ -812,6 +812,9 @@ embedding:
   embed_blacklist_selector:
     default: ''
     hidden: true
+  embed_classname_whitelist:
+    default: 'emoji'
+    hidden: true
 
 legal:
   tos_url:
diff --git a/spec/models/topic_embed_spec.rb b/spec/models/topic_embed_spec.rb
index 8c9b3409d..73ff1490b 100644
--- a/spec/models/topic_embed_spec.rb
+++ b/spec/models/topic_embed_spec.rb
@@ -1,4 +1,5 @@
 require 'spec_helper'
+require 'stringio'
 
 describe TopicEmbed do
 
@@ -30,7 +31,8 @@ describe TopicEmbed do
         expect(post.cooked).to eq(post.raw)
 
         # It converts relative URLs to absolute
-        expect(post.cooked.start_with?("hello world new post <a href=\"http://eviltrout.com/hello\">hello</a> <img src=\"http://eviltrout.com/images/wat.jpg\">")).to eq(true)
+        expect(post.cooked).to have_tag('a', with: { href: 'http://eviltrout.com/hello' })
+        expect(post.cooked).to have_tag('img', with: { src: 'http://eviltrout.com/images/wat.jpg' })
 
         expect(post.topic.has_topic_embed?).to eq(true)
         expect(TopicEmbed.where(topic_id: post.topic_id)).to be_present
@@ -58,4 +60,78 @@ describe TopicEmbed do
 
   end
 
+  describe '.find_remote' do
+
+    context 'post with allowed classes "foo" and "emoji"' do
+
+      let(:user) { Fabricate(:user) }
+      let(:url) { 'http://eviltrout.com/123' }
+      let(:contents) { "my normal size emoji <p class='foo'>Hi</p> <img class='emoji other foo' src='/images/smiley.jpg'>" }
+      let!(:embeddable_host) { Fabricate(:embeddable_host) }
+      let!(:file) { StringIO.new }
+
+      content = ''
+
+      before(:each) do
+        SiteSetting.stubs(:embed_classname_whitelist).returns 'emoji , foo'
+        file.stubs(:read).returns contents
+        TopicEmbed.stubs(:open).returns file
+        title, content = TopicEmbed.find_remote(url)
+      end
+
+      it 'img node has emoji class' do
+        expect(content).to have_tag('img', with: { class: 'emoji' })
+      end
+
+      it 'img node has foo class' do
+        expect(content).to have_tag('img', with: { class: 'foo' })
+      end
+
+      it 'p node has foo class' do
+        expect(content).to have_tag('p', with: { class: 'foo' })
+      end
+
+      it 'nodes removes classes other than emoji' do
+        expect(content).to have_tag('img', without: { class: 'other' })
+      end
+
+    end
+
+    context 'post with no allowed classes' do
+
+      let(:user) { Fabricate(:user) }
+      let(:url) { 'http://eviltrout.com/123' }
+      let(:contents) { "my normal size emoji <p class='foo'>Hi</p> <img class='emoji other foo' src='/images/smiley.jpg'>" }
+      let!(:embeddable_host) { Fabricate(:embeddable_host) }
+      let!(:file) { StringIO.new }
+
+      content = ''
+
+      before(:each) do
+        SiteSetting.stubs(:embed_classname_whitelist).returns ' '
+        file.stubs(:read).returns contents
+        TopicEmbed.stubs(:open).returns file
+        title, content = TopicEmbed.find_remote(url)
+      end
+
+      it 'img node doesn\'t have emoji class' do
+        expect(content).to have_tag('img', without: { class: 'emoji' })
+      end
+
+      it 'img node doesn\'t have foo class' do
+        expect(content).to have_tag('img', without: { class: 'foo' })
+      end
+
+      it 'p node doesn\'t foo class' do
+        expect(content).to have_tag('p', without: { class: 'foo' })
+      end
+
+      it 'img node doesn\'t have other class' do
+        expect(content).to have_tag('img', without: { class: 'other' })
+      end
+
+    end
+
+  end
+
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 701c0de01..30921a6e3 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -42,6 +42,7 @@ Spork.prefork do
     config.fail_fast = ENV['RSPEC_FAIL_FAST'] == "1"
     config.include Helpers
     config.include MessageBus
+    config.include RSpecHtmlMatchers
     config.mock_framework = :mocha
     config.order = 'random'
     config.infer_spec_type_from_file_location!