diff --git a/scripts/default.nix b/scripts/default.nix
index f4c577c..f7f2c55 100644
--- a/scripts/default.nix
+++ b/scripts/default.nix
@@ -145,6 +145,10 @@
     print-battery-icon = [ ];
     controller-battery = [ print-battery-icon ];
     mouse-battery = [ print-battery-icon ];
+    nix-prefetch-firefox-extension = [
+      nix
+    ];
+
     _docker-block-external-connections = [
       iptables
       gawk
diff --git a/scripts/nix-prefetch-firefox-extension b/scripts/nix-prefetch-firefox-extension
new file mode 100755
index 0000000..e98e74d
--- /dev/null
+++ b/scripts/nix-prefetch-firefox-extension
@@ -0,0 +1,7 @@
+#!/bin/sh
+
+set -euo pipefail
+
+hash="$(nix-prefetch-url --type sha256 "$@")"
+
+nix-hash --to-sri --type sha256 "$hash" 2>/dev/null
diff --git a/user/firefox.nix b/user/firefox.nix
index 7a457ed..1dd599c 100644
--- a/user/firefox.nix
+++ b/user/firefox.nix
@@ -139,6 +139,11 @@ in
         };
       };
     };
+
+    home.packages = with pkgs; [
+      nix-prefetch-firefox-extension
+    ];
+
     wayland.windowManager.sway = {
       extraConfig = ''
         exec firefox-devedition