diff --git a/nixos/logical/blackadder.nix b/nixos/logical/blackadder.nix
index 7fea6be..3dc0880 100644
--- a/nixos/logical/blackadder.nix
+++ b/nixos/logical/blackadder.nix
@@ -42,6 +42,7 @@
   virtualisation.docker.enable = true;
   users.users.yorick.extraGroups = [ "docker" ];
 
+  # headphone control
   systemd.services.mdrd = {
     serviceConfig = {
       Type = "dbus";