diff --git a/nix/lib/config/options.nix b/nix/lib/config/options.nix
index 8332cdc..4376b7b 100644
--- a/nix/lib/config/options.nix
+++ b/nix/lib/config/options.nix
@@ -113,6 +113,7 @@ let
     };
     staticIpv4Address = mkOption {
       type = with types; nullOr str;
+      default = null;
     };
     upBandwidth = mkOption {
       type = with types; nullOr int;