diff --git a/nixos/modules/hardware/facter/system.nix b/nixos/modules/hardware/facter/system.nix
index 32648f7d07e4..2019bfa522d3 100644
--- a/nixos/modules/hardware/facter/system.nix
+++ b/nixos/modules/hardware/facter/system.nix
@@ -8,7 +8,10 @@
   # Skip setting hostPlatform if it's read-only
   config.nixpkgs =
     lib.optionalAttrs
-      (config.hardware.facter.report.system or null != null && !options.nixpkgs.hostPlatform.readOnly)
+      (
+        config.hardware.facter.report.system or null != null
+        && !(options.nixpkgs.hostPlatform.readOnly or false)
+      )
       {
         hostPlatform = lib.mkDefault config.hardware.facter.report.system;
       };