diff --git a/lib/tasks/office.rake b/lib/tasks/office.rake
index c6ee8b4dd..8bfc0c0ea 100644
--- a/lib/tasks/office.rake
+++ b/lib/tasks/office.rake
@@ -3,9 +3,9 @@
 namespace :office do
   desc "conver any files to html"
   task :conver => :environment do
-    all_count = Attachment.count
+    all_count = Attachment.where(["container_type IN (?)", %w(Project Course)]).count
     i = 0
-    Attachment.find_each do |a|
+    Attachment.where(["container_type IN (?)", %w(Project Course)]).find_each do |a|
       i += 1
       puts "process [#{i}/#{all_count}] => id #{a.id}"
       saved_path = File.join(Rails.root, "files", "convered_office")