diff --git a/overlays/all.nix b/overlays/all.nix
index 96683828e..815b9010e 100644
--- a/overlays/all.nix
+++ b/overlays/all.nix
@@ -12,7 +12,7 @@ in
 final: prev:
 let
   optional = cond: overlay: if cond then overlay else (_: _: {});
-  isCross = prev.stdenv.hostPlatform != prev.stdenv.buildPlatform;
+  isCross = !(prev.lib.systems.equals prev.stdenv.hostPlatform prev.stdenv.buildPlatform);
   # isCross = !(prev.stdenv.buildPlatform.canExecute prev.stdenv.hostPlatform);
   isStatic = prev.stdenv.hostPlatform.isStatic;
   renderOverlays = overlays: builtins.foldl'
diff --git a/pkgs/by-name/nixpkgs-bootstrap/mkNixpkgs.nix b/pkgs/by-name/nixpkgs-bootstrap/mkNixpkgs.nix
index 2978e2e97..23eedbb56 100644
--- a/pkgs/by-name/nixpkgs-bootstrap/mkNixpkgs.nix
+++ b/pkgs/by-name/nixpkgs-bootstrap/mkNixpkgs.nix
@@ -142,6 +142,9 @@ let
       '';
     };
 
+    elaborate = unpatchedNixpkgs.lib.systems.elaborate;
+    isCross = !(unpatchedNixpkgs.lib.systems.equals (elaborate system) (elaborate localSystem));
+
     nativeNixpkgsArgs = commonNixpkgsArgs // {
       config = {
         allowUnfree = true;  # NIXPKGS_ALLOW_UNFREE=1
@@ -149,7 +152,7 @@ let
         allowUnsupportedSystem = true;  # NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1
       };
     };
-    nixpkgsArgs = nativeNixpkgsArgs // optionalAttrs (system != localSystem) {
+    nixpkgsArgs = nativeNixpkgsArgs // optionalAttrs isCross {
       # XXX(2023/12/11): cache.nixos.org uses `system = ...` instead of `hostPlatform.system`, and that choice impacts the closure of every package.
       # so avoid specifying hostPlatform.system on non-cross builds, so i can use upstream caches.
       crossSystem = system;