diff --git a/nixos/desktop/package-configs/firefox/default.nix b/nixos/desktop/package-configs/firefox/default.nix
index 05fba9a..6bc5aa1 100644
--- a/nixos/desktop/package-configs/firefox/default.nix
+++ b/nixos/desktop/package-configs/firefox/default.nix
@@ -44,6 +44,11 @@
       };
       ExtensionSettings = {
         # "*".installation_mode = "blocked"; # blocks all addons except the ones specified below
+        # Sideberry:
+        "{3c078156-979c-498b-8990-85f7987dd929}" = {
+          install_url = "https://addons.mozilla.org/firefox/downloads/latest/sideberry/latest.xpi";
+          installation_mode = "force_installed";
+        };
         # Privacy Badger:
         "jid1-MnnxcxisBPnSXQ@jetpack" = {
           install_url = "https://addons.mozilla.org/firefox/downloads/latest/privacy-badger17/latest.xpi";