diff --git a/app/helpers/comments_helper.rb b/app/helpers/comments_helper.rb
index 0b5420b98..7af75c72d 100644
--- a/app/helpers/comments_helper.rb
+++ b/app/helpers/comments_helper.rb
@@ -16,7 +16,7 @@ module CommentsHelper
       [
         commentable.user_id,
         commentable.co_author_ids,
-      ].any? { |id| id == comment.user_id }
+      ].flatten.any? { |id| id == comment.user_id }
   end
 
   def get_ama_or_op_banner(commentable)
diff --git a/spec/factories/articles.rb b/spec/factories/articles.rb
index 7a83872a5..ba01e90fa 100644
--- a/spec/factories/articles.rb
+++ b/spec/factories/articles.rb
@@ -18,6 +18,7 @@ FactoryBot.define do
       with_title { true }
       with_collection { nil }
     end
+    co_author_ids { [] }
     association :user, factory: :user, strategy: :create
     description { Faker::Hipster.paragraph(sentence_count: 1)[0..100] }
     main_image    { with_main_image ? Faker::Avatar.image : nil }
diff --git a/spec/system/user_visits_a_comments_page_spec.rb b/spec/system/user_visits_a_comments_page_spec.rb
index a56d68a26..62cdf8db9 100644
--- a/spec/system/user_visits_a_comments_page_spec.rb
+++ b/spec/system/user_visits_a_comments_page_spec.rb
@@ -2,7 +2,9 @@ require "rails_helper"
 
 RSpec.describe "Views an article", type: :system, js: true do
   let(:user) { create(:user) }
-  let(:article) { create(:article, user: user) }
+  let(:co_author) { create(:user) }
+  let(:article) { create(:article, user: user, co_author_ids: [co_author.id]) }
+  let(:ama_article) { create(:article, user: user, tags: "ama") }
 
   let!(:comment) { create(:comment, commentable: article) }
   let!(:child_comment) { create(:comment, parent: comment, commentable: article) }
@@ -12,6 +14,22 @@ RSpec.describe "Views an article", type: :system, js: true do
     visit "#{article.path}/comments"
 
     expect(page).to have_selector(".single-comment-node", visible: :visible, count: 3)
+    expect(page).not_to have_selector(".op-marker")
+  end
+
+  it "shows op marker on author and co-author comments" do
+    create(:comment, user: user, commentable: article)
+    create(:comment, user: co_author, commentable: article)
+    visit "#{article.path}/comments"
+
+    expect(page).to have_selector(".op-marker", visible: :visible, text: "Author", count: 2)
+  end
+
+  it "shows special op marker on ama articles" do
+    create(:comment, user: user, commentable: ama_article)
+    visit "#{ama_article.path}/comments"
+
+    expect(page).to have_selector(".op-marker", visible: :visible, text: "Ask Me Anything")
   end
 
   it "shows a thread" do