diff --git a/Casks/dropin.rb b/Casks/dropin.rb
index f49a3a88b9d..a432e8409b8 100644
--- a/Casks/dropin.rb
+++ b/Casks/dropin.rb
@@ -5,6 +5,7 @@ class Dropin < Cask
   url 'http://excitedatom.com/downloads/dropin/?p=dropin'
   appcast 'http://excitedatom.com/dropin/updates.xml'
   homepage 'http://excitedatom.com/dropin/'
+  license :unknown
 
   app 'DropIn.app'
 end