diff --git a/modules/base.nix b/modules/base.nix
index 38f3bb1..aa504ad 100644
--- a/modules/base.nix
+++ b/modules/base.nix
@@ -12,6 +12,7 @@
     primaryInterface = lib.mkOption {
       type = lib.types.str;
       description = "The primary network interface to use";
+      default = "";
     };
     hostName = lib.mkOption {
       type = lib.types.str;