diff --git a/configuration.nix b/configuration.nix
index 1dd43af..3d5186c 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -19,14 +19,15 @@
   environment.systemPackages = with pkgs; [
     vim
     git
-#    (python3.withPackages (p: with p; [paho-mqtt mido])) # enable for local testing
   ];
 
   systemd.services.mixer-mqtt = {
-    wantedBy = [ "multi-user.target" ]; # auto-start at boot
-
-    serviceConfig = {
-      ExecStart = "${pkgs.python3.withPackages (p: with p; [ paho-mqtt mido ])}/bin/python3 /root/mixer-rpc/mqtt_client.py 172.23.42.20 172.23.42.25";
+    wantedBy = ["multi-user.target"];
+    serviceConfig = let
+      mixer_ip = "172.23.42.20";
+      mqtt_ip = "172.23.42.25";
+    in {
+      ExecStart = "${pkgs.python3.withPackages (p: with p; [ paho-mqtt mido ])}/bin/python3 /root/mixer-rpc/mqtt_client.py ${mixer_ip} ${mqtt_ip}";
       Restart = "always";
       RestartSec = 5;
       Environment = "PYTHONUNBUFFERED=1";