diff --git a/Casks/photoninja.rb b/Casks/photoninja.rb
index 3a446e4fe..851b38230 100644
--- a/Casks/photoninja.rb
+++ b/Casks/photoninja.rb
@@ -4,7 +4,7 @@ cask :v1 => 'photoninja' do
 
   url "https://picturecode.cachefly.net/photoninja/downloads/Install_PhotoNinja_#{version}.dmg"
   homepage 'http://www.picturecode.com/index.php'
-  license :unknown
+  license :unknown    # todo: improve this machine-generated value
 
   app 'PhotoNinja.app'
 end