diff --git a/docs/public/firefox/configure.rst b/docs/public/firefox/configure.rst
index 6d52349..40dcb12 100644
--- a/docs/public/firefox/configure.rst
+++ b/docs/public/firefox/configure.rst
@@ -10,5 +10,6 @@ Client certificates
 .. code:: js
 
  user_pref("browser.tabs.closeWindowWithLastTab", false);
+ user_pref("full-screen-api.warning.timeout", 0);
  user_pref("security.default_personal_cert", "Ask Every Time");
  user_pref("security.default_personal_cert", "Select Automatically");