diff --git a/Casks/thirty-three-rpm.rb b/Casks/thirty-three-rpm.rb
index 49b7399eb..200c708c8 100644
--- a/Casks/thirty-three-rpm.rb
+++ b/Casks/thirty-three-rpm.rb
@@ -4,6 +4,7 @@ class ThirtyThreeRpm < Cask
 
   url 'http://www.edenwaith.com/downloads/33rpm.dmg'
   homepage 'http://www.edenwaith.com/products/33rpm/'
+  license :unknown
 
   app '33 RPM.app'
 end