diff --git a/Casks/grabbox.rb b/Casks/grabbox.rb
index 1955d30ab9b..bdf85d84d16 100644
--- a/Casks/grabbox.rb
+++ b/Casks/grabbox.rb
@@ -3,7 +3,8 @@ class Grabbox < Cask
   sha256 'e6f92efce8585b58d1b5d9afc4a2187e07bf76c14961aff1b83a8422fb342f2f'
 
   url "http://grabbox.devsoft.no/updates/GrabBox%20Beta%20v#{version}.zip"
-  appcast 'http://grabbox.devsoft.no/appcastBeta.xml'
+  appcast 'http://grabbox.devsoft.no/appcastBeta.xml',
+          :sha256 => '8333d48af84e69f3885f7de4cd553c46a6feceadb1e354bf19a9170c277fabfe'
   homepage 'http://grabbox.devsoft.no/'
   license :unknown