diff --git a/Casks/audiobookbinder.rb b/Casks/audiobookbinder.rb
index 94141af0056..9a3f16ce6f3 100644
--- a/Casks/audiobookbinder.rb
+++ b/Casks/audiobookbinder.rb
@@ -5,6 +5,7 @@ class Audiobookbinder < Cask
   url "http://bluezbox.com/audiobookbinder/AudiobookBinder-#{version}.dmg"
   appcast 'http://bluezbox.com/audiobookbinder/appcast.xml'
   homepage 'http://bluezbox.com/audiobookbinder.html'
+  license :unknown
 
   app 'AudioBookBinder.app'
 end