diff --git a/app/models/comment.rb b/app/models/comment.rb
index 6bb9bec..a984540 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -147,10 +147,14 @@ class Comment < ActiveRecord::Base
   def self.as_thread
     result = {}
     root = []
-    all.each do |c|
+    order(:id).each do |c|
       c.replies = []
       result[c.id] ||= c
-      c.reply_of_id.nil? ? root << c : result[c.reply_of_id].replies << c
+      if result[c.reply_of_id]
+        result[c.reply_of_id].replies << c
+      else
+        root << c
+      end
     end
     root
   end
diff --git a/test/unit/comment_test.rb b/test/unit/comment_test.rb
index cbab01e..e06f424 100644
--- a/test/unit/comment_test.rb
+++ b/test/unit/comment_test.rb
@@ -536,6 +536,15 @@ class CommentTest < ActiveSupport::TestCase
     assert_equal c, SpamNotification.marked_as_ham
   end
 
+  should 'ignore spam when constructing threads' do
+    original = create_comment
+    response = create_comment(:reply_of_id => original.id)
+    original.spam!
+
+    assert_equivalent [response], Comment.without_spam.as_thread
+  end
+
+
   should 'store User-Agent' do
     c = Comment.new(:user_agent => 'foo')
     assert_equal 'foo', c.user_agent
--
libgit2 0.21.2