diff --git a/Casks/color-oracle.rb b/Casks/color-oracle.rb
index 4418439d8..052fa4364 100644
--- a/Casks/color-oracle.rb
+++ b/Casks/color-oracle.rb
@@ -4,6 +4,7 @@ class ColorOracle < Cask
 
   url 'http://colororacle.org/ColorOracleMac.zip'
   homepage 'http://colororacle.org/'
+  license :unknown
 
   app 'Color Oracle.app'
 end