diff --git a/pkgs/test/top-level/stage.nix b/pkgs/test/top-level/stage.nix
index 1a28a5aeaa12d6..0fd287cac8a548 100644
--- a/pkgs/test/top-level/stage.nix
+++ b/pkgs/test/top-level/stage.nix
@@ -98,9 +98,8 @@ assert isComposable "pkgsStatic";
 assert isComposable "pkgsi686Linux";
 
 # Special cases regarding buildPlatform vs hostPlatform
-# TODO: fails
-# assert discardEvaluationErrors (pkgsCross.gnu64.pkgsMusl.stdenv.hostPlatform.isMusl);
-# assert discardEvaluationErrors (pkgsCross.gnu64.pkgsi686Linux.stdenv.hostPlatform.isx86_32);
+assert discardEvaluationErrors (pkgsCross.gnu64.pkgsMusl.stdenv.hostPlatform.isMusl);
+assert discardEvaluationErrors (pkgsCross.gnu64.pkgsi686Linux.stdenv.hostPlatform.isx86_32);
 assert discardEvaluationErrors (pkgsCross.mingwW64.pkgsLinux.stdenv.hostPlatform.isLinux);
 assert discardEvaluationErrors (
   pkgsCross.aarch64-darwin.pkgsx86_64Darwin.stdenv.hostPlatform.isx86_64
diff --git a/pkgs/top-level/stage.nix b/pkgs/top-level/stage.nix
index 50ea964844e247..bc810e9e79a895 100644
--- a/pkgs/top-level/stage.nix
+++ b/pkgs/top-level/stage.nix
@@ -191,10 +191,13 @@ let
         (lib.systems.systemToAttrs (lib.defaultTo prevArgs.localSystem prevArgs.crossSystem or null)) // crossAttrs;
     });
     # This is only cross when we are already cross, otherwise local.
-    mkHybridPkgs = name: hybridAttrs: mkPkgs name (prevArgs: {
-      ${if stdenv.hostPlatform == stdenv.buildPlatform then "localSystem" else "crossSystem"} =
-        (lib.systems.systemToAttrs (lib.defaultTo prevArgs.localSystem prevArgs.crossSystem or null)) // hybridAttrs;
-    });
+    # For the case of "native cross", i.e. pkgsCross.gnu64 on a x86_64-linux system, we need to adjust **both**
+    # localSystem **and** crossSystem, otherwise they're out of sync.
+    mkHybridPkgs = name: hybridAttrs: mkPkgs name (prevArgs: let
+        newSystem = (lib.systems.systemToAttrs (lib.defaultTo prevArgs.localSystem prevArgs.crossSystem or null)) // hybridAttrs;
+      in lib.optionalAttrs (stdenv.hostPlatform == stdenv.buildPlatform) { localSystem = newSystem; }
+      // lib.optionalAttrs (prevArgs ? crossSystem) { crossSystem = newSystem; }
+    );
   in self: super: {
     # This maps each entry in lib.systems.examples to its own package
     # set. Each of these will contain all packages cross compiled for