diff --git a/nixos/modules/misc/nixpkgs.nix b/nixos/modules/misc/nixpkgs.nix
index 132a9b68ceb..ad017aff816 100644
--- a/nixos/modules/misc/nixpkgs.nix
+++ b/nixos/modules/misc/nixpkgs.nix
@@ -69,9 +69,9 @@ let
     }'';
 
   legacyOptionsDefined =
-    optional opt.system.isDefined opt.system
-    ++ (optional (opt.localSystem.highestPrio < (mkOptionDefault {}).priority) opt.localSystem)
-    ++ (optional (opt.crossSystem.highestPrio < (mkOptionDefault {}).priority) opt.crossSystem)
+    optional (opt.localSystem.highestPrio < (mkDefault {}).priority) opt.system
+    ++ optional (opt.localSystem.highestPrio < (mkOptionDefault {}).priority) opt.localSystem
+    ++ optional (opt.crossSystem.highestPrio < (mkOptionDefault {}).priority) opt.crossSystem
     ;
 
   defaultPkgs =