diff --git a/Casks/firefox-nightly.rb b/Casks/firefox-nightly.rb
index bee2e55c7..86f47a5fe 100644
--- a/Casks/firefox-nightly.rb
+++ b/Casks/firefox-nightly.rb
@@ -1,4 +1,4 @@
-class FirefoxNightly < Cask
+cask :v1 => 'firefox-nightly' do
   version :latest
   sha256 :no_check