diff --git a/nixos/modules/system/activation/top-level.nix b/nixos/modules/system/activation/top-level.nix
index e9897cc01b6..67cb2264e3f 100644
--- a/nixos/modules/system/activation/top-level.nix
+++ b/nixos/modules/system/activation/top-level.nix
@@ -141,6 +141,7 @@ in
     system.build = mkOption {
       internal = true;
       default = {};
+      type = types.attrs;
       description = ''
         Attribute set of derivations used to setup the system.
       '';
diff --git a/nixos/modules/virtualisation/xen-dom0.nix b/nixos/modules/virtualisation/xen-dom0.nix
index 5239652d407..c7656bc309c 100644
--- a/nixos/modules/virtualisation/xen-dom0.nix
+++ b/nixos/modules/virtualisation/xen-dom0.nix
@@ -16,6 +16,7 @@ in
     virtualisation.xen.enable =
       mkOption {
         default = false;
+        type = types.bool;
         description =
           ''
             Setting this option enables the Xen hypervisor, a