diff --git a/modules/nixos.nix b/modules/nixos.nix
index 4b7f4d9..fa85331 100644
--- a/modules/nixos.nix
+++ b/modules/nixos.nix
@@ -45,7 +45,7 @@
   time.timeZone = "Europe/Berlin";
 
   # Internationalisation properties. Template defaults — override per region.
-  i18n.defaultLocale = "en_US.UTF-8";
+  i18n.defaultLocale = lib.mkDefault "en_US.UTF-8";
   console = {
     font = "Lat2-Terminus16";
     keyMap = "de";