diff --git a/app/models/paper.rb b/app/models/paper.rb
index d8c50132..0fa7b248 100644
--- a/app/models/paper.rb
+++ b/app/models/paper.rb
@@ -115,7 +115,7 @@ class Paper < ApplicationRecord
     'HTML',
     'CSS',
     'CMake',
-    'Ruby'
+    'Ruby',
     'Dockerfile',
     'Batchfile'
   ].freeze