diff --git a/packages.nix b/packages.nix
index 2dcf057e..3967cee2 100644
--- a/packages.nix
+++ b/packages.nix
@@ -110,16 +110,16 @@ lib.attrsets.mapAttrs
         "${name}-nixos-rebuild" = pkgs.writeScriptBin "${name}-nixos-rebuild" ''
           set -eou pipefail
 
-          if nix eval .#nixosConfigurations.${name}.config.c3d2.deployment.server &>/dev/null; then
+          ${lib.optionalString (hostConfig.c3d2.deployment.server != "") ''
             echo "microvms cannot be updated with nixos-rebuild. Use nix run .#microvm-update-${name}"
             exit 2
-          fi
+          ''}
 
           [[ $(ssh ${target} cat /etc/hostname) == ${name} ]]
           nix copy --no-check-sigs --to ssh-ng://${target} ${inputPaths}
 
           # use nixos-rebuild from target config
-          nixosRebuild=$(ssh ${target} nix build ${discardStringCtx hostConfig.system.build.nixos-rebuild.outPath} ${overrideInputsArgs} --no-link --json | ${lib.getExe hostPkgs.jq} -r '.[0].outputs.out')
+          nixosRebuild=$(ssh ${target} nix build ${discardStringCtx hostConfig.system.build.nixos-rebuild.outPath or ""} ${overrideInputsArgs} --no-link --json | ${lib.getExe hostPkgs.jq} -r '.[0].outputs.out')
           ssh ${target} $nixosRebuild/bin/nixos-rebuild ${rebuildArg} "$@"
         '';