diff --git a/modules/common.nix b/modules/common.nix
index ef5feb2..e7ef71d 100644
--- a/modules/common.nix
+++ b/modules/common.nix
@@ -1,8 +1,9 @@
 # Modules common to all systems
 {
-  pkgs,
   config,
   inputs,
+  lib,
+  pkgs,
   ...
 }:
 
@@ -15,13 +16,27 @@
       zellij # Terminal multiplexer
     ];
 
-    # Allow packages from the unstable repo by using 'pkgs.unstable'
     nixpkgs.overlays = [
       (final: _prev: {
+        # Allow packages from the unstable repo by using 'pkgs.unstable'
         unstable = import inputs.nixpkgs-unstable {
           system = final.system;
           config.allowUnfree = true;
         };
+
+        # Define custom functions using 'pkgs.util'
+        util = {
+          # Parses the domain from a URL
+          getDomainFromURL =
+            url:
+            let
+              parsedURL = (lib.strings.splitString "." url);
+            in
+            builtins.concatStringsSep "." [
+              (builtins.elemAt parsedURL 1)
+              (builtins.elemAt parsedURL 2)
+            ];
+        };
       })
     ];
 
diff --git a/modules/services/airsonic.nix b/modules/services/airsonic.nix
index fd45802..31af51f 100644
--- a/modules/services/airsonic.nix
+++ b/modules/services/airsonic.nix
@@ -31,14 +31,7 @@ in
 
     services = {
       nginx.virtualHosts."${cfg.url}" = {
-        useACMEHost =
-          let
-            parsedURL = (lib.strings.splitString "." cfg.url);
-          in
-          builtins.concatStringsSep "." [
-            (builtins.elemAt parsedURL 1)
-            (builtins.elemAt parsedURL 2)
-          ];
+        useACMEHost = pkgs.util.getDomainFromURL cfg.url;
         forceSSL = true;
         locations."/" = {
           proxyPass = "http://127.0.0.1:4040";
diff --git a/modules/services/deluge.nix b/modules/services/deluge.nix
index 26555b8..03e2043 100644
--- a/modules/services/deluge.nix
+++ b/modules/services/deluge.nix
@@ -1,4 +1,9 @@
-{ config, lib, ... }:
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
 
 let
   cfg = config.aux.system.services.deluge;
@@ -25,14 +30,7 @@ in
   config = lib.mkIf cfg.enable {
     services = {
       nginx.virtualHosts."${cfg.url}" = {
-        useACMEHost =
-          let
-            parsedURL = (lib.strings.splitString "." cfg.url);
-          in
-          builtins.concatStringsSep "." [
-            (builtins.elemAt parsedURL 1)
-            (builtins.elemAt parsedURL 2)
-          ];
+        useACMEHost = pkgs.util.getDomainFromURL cfg.url;
         forceSSL = true;
         locations."/" = {
           proxyPass = "http://127.0.0.1:8112";
diff --git a/modules/services/forgejo.nix b/modules/services/forgejo.nix
index 03b2cb5..2cffb0f 100644
--- a/modules/services/forgejo.nix
+++ b/modules/services/forgejo.nix
@@ -72,14 +72,7 @@ in
       } // lib.optionalAttrs (cfg.home != null) { stateDir = cfg.home; };
 
       nginx.virtualHosts."${cfg.url}" = {
-        useACMEHost =
-          let
-            parsedURL = (lib.strings.splitString "." cfg.url);
-          in
-          builtins.concatStringsSep "." [
-            (builtins.elemAt parsedURL 1)
-            (builtins.elemAt parsedURL 2)
-          ];
+        useACMEHost = pkgs.util.getDomainFromURL cfg.url;
         forceSSL = true;
         locations."/" = {
           proxyPass = "http://127.0.0.1:3000";
diff --git a/modules/services/home-assistant.nix b/modules/services/home-assistant.nix
index 86ade25..03cd5e8 100644
--- a/modules/services/home-assistant.nix
+++ b/modules/services/home-assistant.nix
@@ -1,4 +1,9 @@
-{ config, lib, ... }:
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
 
 let
   cfg = config.aux.system.services.home-assistant;
@@ -49,14 +54,7 @@ in
         };
       };
       nginx.virtualHosts."${cfg.url}" = {
-        useACMEHost =
-          let
-            parsedURL = (lib.strings.splitString "." cfg.url);
-          in
-          builtins.concatStringsSep "." [
-            (builtins.elemAt parsedURL 1)
-            (builtins.elemAt parsedURL 2)
-          ];
+        useACMEHost = pkgs.util.getDomainFromURL cfg.url;
         forceSSL = true;
         locations."/" = {
           proxyPass = "http://[::1]:8123";
diff --git a/modules/services/jellyfin.nix b/modules/services/jellyfin.nix
index 672ca4f..718229e 100644
--- a/modules/services/jellyfin.nix
+++ b/modules/services/jellyfin.nix
@@ -2,6 +2,7 @@
   pkgs,
   config,
   lib,
+  self,
   ...
 }:
 let
@@ -34,14 +35,7 @@ in
 
     services = {
       nginx.virtualHosts."${cfg.url}" = {
-        useACMEHost =
-          let
-            parsedURL = (lib.strings.splitString "." cfg.url);
-          in
-          builtins.concatStringsSep "." [
-            (builtins.elemAt parsedURL 1)
-            (builtins.elemAt parsedURL 2)
-          ];
+        useACMEHost = pkgs.util.getDomainFromURL cfg.url;
         forceSSL = true;
         locations."/" = {
           proxyPass = "http://127.0.0.1:8096";
diff --git a/modules/services/netdata.nix b/modules/services/netdata.nix
index 9d1997c..f35ab60 100644
--- a/modules/services/netdata.nix
+++ b/modules/services/netdata.nix
@@ -50,14 +50,7 @@ in
     (lib.mkIf (cfg.enable && cfg.type == "parent") {
       services = {
         nginx.virtualHosts."${cfg.url}" = {
-          useACMEHost =
-            let
-              parsedURL = (lib.strings.splitString "." cfg.url);
-            in
-            builtins.concatStringsSep "." [
-              (builtins.elemAt parsedURL 1)
-              (builtins.elemAt parsedURL 2)
-            ];
+          useACMEHost = pkgs.util.getDomainFromURL cfg.url;
           forceSSL = true;
           basicAuth = {
             "${cfg.auth.user}" = cfg.auth.password;