diff --git a/Casks/midikeys.rb b/Casks/midikeys.rb
index fa19eb09e36..e1d872a3634 100644
--- a/Casks/midikeys.rb
+++ b/Casks/midikeys.rb
@@ -7,7 +7,7 @@ cask :v1 => 'midikeys' do
   appcast 'http://immosw.com/versions/midikeys/appcast.xml',
           :sha256 => '87a8ce2e45af98924bfa75dcd851579a1096a0e7d5b5d92498ec77df2d4cf283'
   homepage 'http://www.manyetas.com/creed/midikeys.html'
-  license :unknown    # todo: change license and remove this comment; ':unknown' is a machine-generated placeholder
+  license :gratis
 
   app 'MidiKeys/MidiKeys.app'
 end