diff --git a/hosts/telefonmann/default.nix b/hosts/telefonmann/default.nix
index 1ac9b93..53bbeb2 100644
--- a/hosts/telefonmann/default.nix
+++ b/hosts/telefonmann/default.nix
@@ -1,4 +1,7 @@
-{ config, ... }: {
+{ config, ... }:
+let
+  address = "10.0.10.2";
+in {
   imports = [
     ./hardware.nix
     ./disko.nix
@@ -9,14 +12,14 @@
 
   networking.interfaces.ens19 = {
     ipv4.addresses = [{
-      address = "10.0.10.2";
+      address = address;
       prefixLength = 24;
     }];
   };
 
   services.voip = {
     enable        = true;
-    serverAddress = "10.0.10.2";
+    serverAddress = address;
     ntpServer     = "10.0.10.1";
 
     # directoryName = "tel.baubs.net";  # shown in phone directory title and HTML page header