diff --git a/Casks/zterm.rb b/Casks/zterm.rb
index 7891ce067..4a784d240 100644
--- a/Casks/zterm.rb
+++ b/Casks/zterm.rb
@@ -4,6 +4,7 @@ class Zterm < Cask
 
   url "http://www.dalverson.com/zterm/ZTerm#{version}.dmg"
   homepage 'http://www.dalverson.com/zterm/'
+  license :unknown
 
   app 'ZTerm.app'
 end