diff --git a/modules/nix/nixpkgs.nix b/modules/nix/nixpkgs.nix
index fa156a5..d4fa306 100644
--- a/modules/nix/nixpkgs.nix
+++ b/modules/nix/nixpkgs.nix
@@ -73,7 +73,10 @@ let
   defaultPkgs =
     if opt.hostPlatform.isDefined then
       let
-        isCross = cfg.buildPlatform != cfg.hostPlatform;
+        isCross =
+          !(lib.systems.equals (lib.systems.elaborate cfg.buildPlatform) (
+            lib.systems.elaborate cfg.hostPlatform
+          ));
         systemArgs =
           if isCross then
             {
@@ -165,13 +168,10 @@ in
     };
 
     hostPlatform = lib.mkOption {
-      type = lib.types.either lib.types.str lib.types.attrs; # TODO utilize lib.systems.parsedPlatform
+      type = lib.types.either lib.types.str lib.types.attrs;
       example = {
         system = "aarch64-darwin";
       };
-      # Make sure that the final value has all fields for sake of other modules
-      # referring to this. TODO make `lib.systems` itself use the module system.
-      apply = lib.systems.elaborate;
       description = ''
         Specifies the platform where the nix-darwin configuration will run.
 
@@ -182,24 +182,13 @@ in
     };
 
     buildPlatform = lib.mkOption {
-      type = lib.types.either lib.types.str lib.types.attrs; # TODO utilize lib.systems.parsedPlatform
+      type = lib.types.either lib.types.str lib.types.attrs;
       default = cfg.hostPlatform;
       example = {
         system = "x86_64-darwin";
       };
       # Make sure that the final value has all fields for sake of other modules
       # referring to this.
-      apply =
-        inputBuildPlatform:
-        let
-          elaborated = lib.systems.elaborate inputBuildPlatform;
-        in
-        if lib.systems.equals elaborated cfg.hostPlatform then
-          cfg.hostPlatform # make identical, so that `==` equality works;
-            see
-            "https://github.com/NixOS/nixpkgs/issues/278001"
-        else
-          elaborated;
       defaultText = lib.literalExpression ''config.nixpkgs.hostPlatform'';
       description = ''
         Specifies the platform on which nix-darwin should be built.
@@ -323,6 +312,16 @@ in
           ${lib.concatMapStringsSep "\n" (file: "  - ${file}") opt.config.files}
         '';
       }
+      {
+        assertion =
+          (opt.hostPlatform.isDefined -> builtins.isAttrs cfg.buildPlatform -> !(cfg.buildPlatform ? parsed))
+          && (opt.hostPlatform.isDefined -> builtins.isAttrs cfg.hostPlatform -> !(cfg.hostPlatform ? parsed));
+        message = ''
+          Passing fully elaborated systems to `nixpkgs.localSystem`, `nixpkgs.crossSystem`, `nixpkgs.buildPlatform`
+          or `nixpkgs.hostPlatform` will break composability of package sets in nixpkgs. For example, pkgs.pkgsStatic
+          would not work in modules anymore.
+        '';
+      }
     ];
   };
 }