diff --git a/Casks/firefox-aurora.rb b/Casks/firefox-aurora.rb
index d4f7f5c8e..f6b2ec565 100644
--- a/Casks/firefox-aurora.rb
+++ b/Casks/firefox-aurora.rb
@@ -4,6 +4,7 @@ class FirefoxAurora < Cask
 
   url "https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-mozilla-aurora/firefox-#{version}.en-US.mac.dmg"
   homepage 'https://www.mozilla.org/en-US/firefox/aurora/'
+  license :oss
 
   app 'FirefoxAurora.app'
 end