diff --git a/modules/firefox.nix b/modules/firefox.nix
index 21988d3..ce9d2c7 100644
--- a/modules/firefox.nix
+++ b/modules/firefox.nix
@@ -28,6 +28,12 @@
           # Don't ask to save passwords/logins.
           "signon.rememberSignons" = false;
 
+          # Global Privacy Control.
+          # The extension "Privacy Badger" enables this for us as well.
+          # https://blog.mozilla.org/netpolicy/2021/10/28/implementing-global-privacy-control/
+          #"privacy.globalprivacycontrol.enabled" = true;
+          #"privacy.globalprivacycontrol.functionality.enabled" = true;
+
           # https://wiki.archlinux.org/title/Firefox/Privacy#Tracking_protection
           "privacy.trackingprotection.enabled" = true;
           #"privacy.trackingprotection.emailtracking.enabled" = true;
@@ -101,6 +107,11 @@
         # https://nur.nix-community.org/repos/rycee/
         extensions = with pkgs.nur.repos.rycee.firefox-addons; [
           ublock-origin
+          # Automatically learns to block invisible trackers.
+          # Activates "Global Privacy Control" and "Do Not Track".
+          # It is compatible with oter ad-blockers: https://privacybadger.org/#Is-Privacy-Badger-compatible-with-other-extensions%2c-including-other-adblockers
+          privacy-badger
+          # Sync bookmarks with Nextcloud.
           floccus
           snowflake
           simple-tab-groups