diff --git a/flake.nix b/flake.nix
index 6df0a36..d4236b6 100644
--- a/flake.nix
+++ b/flake.nix
@@ -100,6 +100,16 @@
       nixosconf = self.nixosConfigurations.lagarto-ox;
       syspkgs = nixosconf.pkgs;
       build = nixosconf.config.system.build;
+
+      buildRoots = savePkgs:
+        let
+          pkgs = syspkgs;
+          buildInner = { package, attr }: pkgs.linkFarmFromDrvs "${package.name}.${attr}" package.${attr};
+        in pkgs.linkFarmFromDrvs "top-level" (pkgs.lib.mapCartesianProduct buildInner {
+          package = savePkgs;
+          attr = [ "buildInputs" "nativeBuildInputs" ];
+        });
+
     in syspkgs.mkShell {
       pname = "lagarto-ox-shell";
       TOPLEVEL = build.toplevel;
@@ -110,6 +120,7 @@
       UBOOT_ENV = syspkgs.uboot-env;
       BITSTREAM = syspkgs.bitstream;
       BOOTROM = syspkgs.bootrom;
+      GCROOT = buildRoots [ build.toplevel build.kernel ];
       shellHook = ''
         echo "Here are the current system pieces:"
         echo " TOPLEVEL  = $TOPLEVEL"
@@ -120,6 +131,7 @@
         echo " UBOOT_ENV = $UBOOT_ENV"
         echo " BITSTREAM = $BITSTREAM"
         echo " BOOTROM   = $BOOTROM"
+        echo " GCROOT    = $GCROOT"
       '';
     };