diff --git a/build/toolchain/toolchain-bundle/default.nix b/build/toolchain/toolchain-bundle/default.nix
index 794b6d2..1b016c5 100644
--- a/build/toolchain/toolchain-bundle/default.nix
+++ b/build/toolchain/toolchain-bundle/default.nix
@@ -1,53 +1,110 @@
-{ pkgs ? import ../../../third_party/nix/default.nix { } }: with pkgs;
-symlinkJoin {
+let
+  # We want our overrides to only apply when building for static environments.
+  conditionalOverlay = condition: overlay: (if condition then overlay else { });
+
+  pkgs = import ../../../third_party/nix/default.nix {
+    overlays = [
+      # Overrides for allowing static builds
+      (self: super: conditionalOverlay super.stdenv.hostPlatform.isStatic (with self; {
+        # A minimal version of qemu allowing for static builds.
+        qemu-minimal = self.callPackage ./pkgs/qemu { inherit super; };
+
+        # Static perl builds are a rabbit hole as they need patches
+        # and use of undocumented options. Check the derivation for more infos.
+        perl = self.callPackage ./pkgs/perl { inherit super; };
+
+        # Bison requires an override for not hardcoding nix paths.
+        bison = self.callPackage ./pkgs/bison { inherit super; };
+
+        # Provide a custom minimal version of util-linux
+        util-linux-minimal = super.util-linux.override (old: {
+          pamSupport = false;
+          ncursesSupport = false;
+          capabilitiesSupport = false;
+          systemdSupport = false;
+          translateManpages = false;
+          nlsSupport = false;
+          shadowSupport = false;
+          writeSupport = false;
+        });
+
+        # Revert "fixup" which hardcodes a nix path.
+        python3Minimal = super.python3Minimal.overrideAttrs (old: {
+          postPatch = old.postPatch + ''
+            substituteInPlace Lib/subprocess.py \
+              --replace-fail "'${bashNonInteractive}/bin/sh'" "'/bin/sh'"
+          '';
+        });
+
+        # Disable tests as they fail when static build.
+        diffutils = super.diffutils.overrideAttrs (_: {
+          doCheck = false;
+          doInstallCheck = false;
+        });
+
+        # vde2 currently doesn't build without these additional flags.
+        vde2 = super.vde2.overrideAttrs (oldAttrs: {
+          env.NIX_CFLAGS_COMPILE = (oldAttrs.NIX_CFLAGS_COMPILE or "") + " -Wno-error=int-conversion -Wno-error=implicit-function-declaration";
+        });
+      }))
+    ];
+
+    config.replaceCrossStdenv = { buildPackages, baseStdenv }:
+      (buildPackages.withCFlags [ "-fPIC" ]) baseStdenv;
+  };
+
+  # All platforms we want to build for.
+  mkPlatforms = platforms: with platforms; [
+    aarch64-multiplatform-musl
+    musl64
+  ];
+
+  # All packages that we want in our bundle.
+  mkPackages = platformPkgs: with platformPkgs; [
+    gnumake
+    flex
+    bison
+    lz4
+    busybox
+    findutils
+    bc
+    util-linux-minimal # custom pkg
+    perl
+    nasm
+    acpica-tools
+    patch
+    diffutils
+    qemu-minimal # custom pkg
+    m4
+    strace
+    python3Minimal
+  ];
+
+  mkPackagesEnv = platform: pkgs.buildEnv {
+    name = "toolchain-${platform.hostPlatform.config}";
+    paths = mkPackages platform.pkgsStatic;
+  };
+
+  mkBundle = platform: pkgs.stdenv.mkDerivation rec {
+    name = "toolchain-bundle-${platform.hostPlatform.config}";
+    buildInputs = [ pkgs.gnutar pkgs.zstd ];
+
+    phases = [ "buildPhase" ];
+    buildPhase =
+      let
+        merged = mkPackagesEnv platform;
+      in
+      ''
+        mkdir $out
+        tar --zstd --sort=name --hard-dereference -hcf $out/${name}.tar.zst -C ${merged} .
+      '';
+  };
+in
+with pkgs; symlinkJoin {
   name = "toolchain";
   paths =
     let
-      platforms = with pkgsCross; [
-        aarch64-multiplatform-musl
-        musl64
-      ];
+      platforms = mkPlatforms pkgs.pkgsCross;
     in
-    map
-      (platform: (
-        let
-          merged = buildEnv {
-            name = "toolchain-env";
-            paths = with platform.pkgsStatic; [
-              gnumake
-              flex
-              bison
-              lz4
-              busybox
-              findutils
-              bc
-              util-linux-minimal # custom pkg
-              perl
-              nasm
-              acpica-tools
-              patch
-              diffutils
-              qemu-minimal # custom pkg
-              m4
-              strace
-              python3Minimal
-            ];
-          };
-        in
-        stdenv.mkDerivation rec {
-          name = "toolchain-bundle";
-          buildInputs = [ gnutar zstd ];
-
-          phases = [ "buildPhase" "installPhase" ];
-          buildPhase = ''
-            tar --zstd --sort=name --hard-dereference -hcf bundle.tar.zst -C ${merged} .
-          '';
-
-          installPhase = ''
-            mkdir $out
-            mv bundle.tar.zst $out/${name}-${platform.hostPlatform.config}.tar.zst
-          '';
-        }
-      ))
-      platforms;
+    map mkBundle platforms;
 }
diff --git a/third_party/nix/pkgs/bison/BUILD.bazel b/build/toolchain/toolchain-bundle/pkgs/bison/BUILD.bazel
similarity index 100%
rename from third_party/nix/pkgs/bison/BUILD.bazel
rename to build/toolchain/toolchain-bundle/pkgs/bison/BUILD.bazel
diff --git a/third_party/nix/pkgs/bison/default.nix b/build/toolchain/toolchain-bundle/pkgs/bison/default.nix
similarity index 61%
rename from third_party/nix/pkgs/bison/default.nix
rename to build/toolchain/toolchain-bundle/pkgs/bison/default.nix
index 8b2245e..9132a30 100644
--- a/third_party/nix/pkgs/bison/default.nix
+++ b/build/toolchain/toolchain-bundle/pkgs/bison/default.nix
@@ -1,6 +1,5 @@
-{ pkgs }: with pkgs;
-if (!stdenv.hostPlatform.isStatic) then bison else
-bison.overrideAttrs (old: {
+{ super, ... }:
+super.bison.overrideAttrs (_: {
   # Check overrided file for more informations
   postPatch = ''
     cp ${./yacc.in} src/yacc.in
diff --git a/third_party/nix/pkgs/bison/yacc.in b/build/toolchain/toolchain-bundle/pkgs/bison/yacc.in
similarity index 100%
rename from third_party/nix/pkgs/bison/yacc.in
rename to build/toolchain/toolchain-bundle/pkgs/bison/yacc.in
diff --git a/third_party/nix/pkgs/perl/BUILD.bazel b/build/toolchain/toolchain-bundle/pkgs/perl/BUILD.bazel
similarity index 100%
rename from third_party/nix/pkgs/perl/BUILD.bazel
rename to build/toolchain/toolchain-bundle/pkgs/perl/BUILD.bazel
diff --git a/third_party/nix/pkgs/perl/default.nix b/build/toolchain/toolchain-bundle/pkgs/perl/default.nix
similarity index 72%
rename from third_party/nix/pkgs/perl/default.nix
rename to build/toolchain/toolchain-bundle/pkgs/perl/default.nix
index c2677b5..e8f5a0d 100644
--- a/third_party/nix/pkgs/perl/default.nix
+++ b/build/toolchain/toolchain-bundle/pkgs/perl/default.nix
@@ -1,5 +1,9 @@
-{ pkgs }: with pkgs;
-if (!stdenv.hostPlatform.isStatic) then perl else
+{ lib, super, ... }@inputs:
+let
+  # Passthrough default configuration without our custom super attribute. Perl
+  # requires itself which breaks when we don't pass through the default attributes.
+  perl = super.perl.override (_: (lib.filterAttrs (name: _: name != "super") inputs));
+in
 perl.overrideAttrs (old: {
   patches = old.patches ++ [
     ./static_build.patch
diff --git a/third_party/nix/pkgs/perl/static_build.patch b/build/toolchain/toolchain-bundle/pkgs/perl/static_build.patch
similarity index 100%
rename from third_party/nix/pkgs/perl/static_build.patch
rename to build/toolchain/toolchain-bundle/pkgs/perl/static_build.patch
diff --git a/third_party/nix/pkgs/qemu/BUILD.bazel b/build/toolchain/toolchain-bundle/pkgs/qemu/BUILD.bazel
similarity index 100%
rename from third_party/nix/pkgs/qemu/BUILD.bazel
rename to build/toolchain/toolchain-bundle/pkgs/qemu/BUILD.bazel
diff --git a/third_party/nix/pkgs/qemu/default.nix b/build/toolchain/toolchain-bundle/pkgs/qemu/default.nix
similarity index 94%
rename from third_party/nix/pkgs/qemu/default.nix
rename to build/toolchain/toolchain-bundle/pkgs/qemu/default.nix
index 5134cb7..81f8825 100644
--- a/third_party/nix/pkgs/qemu/default.nix
+++ b/build/toolchain/toolchain-bundle/pkgs/qemu/default.nix
@@ -1,5 +1,4 @@
-{ pkgs }: with pkgs;
-
+{ qemu_kvm, audit, ... }:
 let
   qemuMinimal = qemu_kvm.override (old: {
     hostCpuOnly = true;
@@ -43,6 +42,6 @@
   configureFlags = (builtins.filter (v: v != "--static") old.configureFlags) ++ [ "--disable-libcbor" ];
   strictDeps = true;
   # a private dependency of PAM which is not linked explicitly in static builds
-  buildInputs = old.buildInputs ++ [ pkgs.audit ];
+  buildInputs = old.buildInputs ++ [ audit ];
   env.NIX_LDFLAGS = " -laudit ";
 })
diff --git a/third_party/nix/pkgs/qemu/static_build_crc32c_duplicate_definition.patch b/build/toolchain/toolchain-bundle/pkgs/qemu/static_build_crc32c_duplicate_definition.patch
similarity index 100%
rename from third_party/nix/pkgs/qemu/static_build_crc32c_duplicate_definition.patch
rename to build/toolchain/toolchain-bundle/pkgs/qemu/static_build_crc32c_duplicate_definition.patch
diff --git a/third_party/nix/default.nix b/third_party/nix/default.nix
index 726119e..f2650b3 100644
--- a/third_party/nix/default.nix
+++ b/third_party/nix/default.nix
@@ -1,27 +1,13 @@
-{ sources ? import ./sources.nix }:
+{ sources ? import ./sources.nix, overlays ? [ ], config ? { } }:
 let
   pkgs = import sources.nixpkgs
     {
-      overlays = [
+      overlays = overlays ++ [
         (self: super: {
-          qemu-minimal = import ./pkgs/qemu { pkgs = super; };
-          diffutils = import ./pkgs/diffutils { pkgs = super; };
-          util-linux-minimal = import ./pkgs/util-linux { pkgs = super; };
-          bazel-unwrapped = import ./pkgs/bazel { pkgs = super; };
-          perl = import ./pkgs/perl { pkgs = super; };
           bazel_8 = self.callPackage ./pkgs/bazel_8/package.nix { };
-          python3Minimal = import ./pkgs/python3 { pkgs = super; };
-          bison = import ./pkgs/bison { pkgs = super; };
-        })
-        (self: super: {
-          vde2 = super.vde2.overrideAttrs (oldAttrs: {
-            env.NIX_CFLAGS_COMPILE = (oldAttrs.NIX_CFLAGS_COMPILE or "") + " -Wno-error=int-conversion -Wno-error=implicit-function-declaration";
-          });
         })
       ];
-
-      config.replaceCrossStdenv = { buildPackages, baseStdenv }:
-        (buildPackages.withCFlags [ "-fPIC" ]) baseStdenv;
+      config = config;
     };
 in
 pkgs // {
diff --git a/third_party/nix/pkgs/diffutils/BUILD.bazel b/third_party/nix/pkgs/diffutils/BUILD.bazel
deleted file mode 100644
index e69de29..0000000
--- a/third_party/nix/pkgs/diffutils/BUILD.bazel
+++ /dev/null
diff --git a/third_party/nix/pkgs/diffutils/default.nix b/third_party/nix/pkgs/diffutils/default.nix
deleted file mode 100644
index bbb38e3..0000000
--- a/third_party/nix/pkgs/diffutils/default.nix
+++ /dev/null
@@ -1,39 +0,0 @@
-{ pkgs }: with pkgs;
-if (!stdenv.hostPlatform.isStatic) then diffutils else
-diffutils.overrideAttrs (old: {
-  # Disable tests as they fail when static build.
-
-  # FAIL: test-getopt-gnu
-  #=====================
-  #
-  #test-getopt.h:661: assertion 'optind == 2' failed
-  #FAIL test-getopt-gnu (exit status: 134)
-  #
-  #FAIL: test-getopt-posix
-  #=======================
-  #
-  #test-getopt.h:661: assertion 'optind == 2' failed
-  #FAIL test-getopt-posix (exit status: 134)
-  #
-  #FAIL: test-nl_langinfo-mt
-  #=========================
-  #
-  #FAIL test-nl_langinfo-mt (exit status: 134)
-  #
-  #FAIL: test-random-mt
-  #====================
-  #
-  #FAIL test-random-mt (exit status: 134)
-  #
-  #FAIL: test-setlocale_null-mt-one
-  #================================
-  #
-  #FAIL test-setlocale_null-mt-one (exit status: 134)
-  #
-  #FAIL: test-setlocale_null-mt-all
-  #================================
-  #
-  #FAIL test-setlocale_null-mt-all (exit status: 134)
-  doCheck = false;
-  doInstallCheck = false;
-})
diff --git a/third_party/nix/pkgs/python3/BUILD.bazel b/third_party/nix/pkgs/python3/BUILD.bazel
deleted file mode 100644
index e69de29..0000000
--- a/third_party/nix/pkgs/python3/BUILD.bazel
+++ /dev/null
diff --git a/third_party/nix/pkgs/python3/default.nix b/third_party/nix/pkgs/python3/default.nix
deleted file mode 100644
index 3102b88..0000000
--- a/third_party/nix/pkgs/python3/default.nix
+++ /dev/null
@@ -1,10 +0,0 @@
-{ pkgs }: with pkgs;
-# Only override for our actual build
-if (!stdenv.hostPlatform.isStatic) then python3Minimal else
-python3Minimal.overrideAttrs (old: {
-  # Revert "fixup" which hardcodes a nix path.
-  postPatch = old.postPatch + ''
-    substituteInPlace Lib/subprocess.py \
-      --replace-fail "'${bashNonInteractive}/bin/sh'" "'/bin/sh'"
-  '';
-})
diff --git a/third_party/nix/pkgs/util-linux/BUILD.bazel b/third_party/nix/pkgs/util-linux/BUILD.bazel
deleted file mode 100644
index e69de29..0000000
--- a/third_party/nix/pkgs/util-linux/BUILD.bazel
+++ /dev/null
diff --git a/third_party/nix/pkgs/util-linux/default.nix b/third_party/nix/pkgs/util-linux/default.nix
deleted file mode 100644
index 1935cd3..0000000
--- a/third_party/nix/pkgs/util-linux/default.nix
+++ /dev/null
@@ -1,11 +0,0 @@
-{ pkgs }: with pkgs;
-util-linux.override (old: {
-  pamSupport = false;
-  ncursesSupport = false;
-  capabilitiesSupport = false;
-  systemdSupport = false;
-  translateManpages = false;
-  nlsSupport = false;
-  shadowSupport = false;
-  writeSupport = false;
-})