diff --git a/default.nix b/default.nix
index 2b1a763..59758ae 100644
--- a/default.nix
+++ b/default.nix
@@ -1,32 +1,34 @@
 {
-    nixPkgsVersion ? "3e52e76b70d5508f3cec70b882a29199f4d1ee85"
+    nixPkgsVersion ? "f606c027310f06df398875960e04038db1f0129f", # release 23.0 # "3e52e76b70d5508f3cec70b882a29199f4d1ee85",  # unstable
+    currentSystem
 }:
 let
 
     getNixPkgs = args: import (builtins.fetchGit {
         name = "nixpkg-serene-${nixPkgsVersion}";
         url = "https://github.com/nixos/nixpkgs/";
-        # Commit hash for nixos-unstable as of 2018-09-12
         # `git ls-remote https://github.com/nixos/nixpkgs nixos-unstable`
-        ref = "refs/heads/nixos-unstable";
+        ref = "refs/heads/release-23.05"; # refs/heads/nixos-unstable
         rev = nixPkgsVersion;
     }) args;
 
-    nixpkgs = getNixPkgs {};
-    system = import ./system.nix { pkgs = nixpkgs; };
-    staticMuslPkgs = getNixPkgs system;
-    llvm = staticMuslPkgs.llvmPackages_16.override { stdenv = staticMuslPkgs.llvmPackages_16.libcxxClang; };
-    SereneOverlay = final: prev:
-        {
-              sereneToolchain = llvm.libcxxClang;
-        };
+    nixpkgs = getNixPkgs { system = currentSystem; };
+    system = import ./system.nix {
+        pkgs = nixpkgs;
+        inherit currentSystem;
+    };
+    # staticMuslPkgs = getNixPkgs system;
+    # llvm = staticMuslPkgs.llvmPackages_16.override { stdenv = staticMuslPkgs.llvmPackages_16.libcxxStdenv; };
+
+    replaceStdenv = { pkgs }:
+        let
+            llvm = pkgs.llvmPackages_16.override { stdenv = pkgs.llvmPackages_16.libcxxStdenv; };
+        in
+          llvm.libcxxStdenv;
+
+    createPkgSet = _:
+        getNixPkgs (system // { config = { inherit replaceStdenv; }; });
 
-    createPkgSet = _: # It has to be the nixpkgs instance
-        getNixPkgs (system // { overlays = [ SereneOverlay ]; });
-    #pkgs = getNixPkgs nixVersion (system // { overlays = [ libcxxClangOverlay ]; });
 in {
-    inherit SereneOverlay createPkgSet;
-    # setupToolchain = nixpkgs:
-
-    #pkgs.stdenv.override { stdenv = llvm.libcxxClang; };
+    inherit createPkgSet;
 }
diff --git a/flake.nix b/flake.nix
index 10a3cdf..1ab6a1a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,10 +4,19 @@
 
   outputs = inputs:
       let
-          toolchain = import ./.;
+          toolchain = import /home/lxsameer/src/toolchain/test-stdenv.nix {};
+          nixpkgs = import /home/lxsameer/src/nixpkgs {};
+          myenv = toolchain.createPkgSet;
       in
-      {
-          inherit toolchain;
-      };
-
+        {
+            testClang = myenv.stdenv.mkDerivation {
+                name = "testClang";
+                unpackPhase = "echo AA $CC; echo '--'; env; NIX_DEBUG=1 $CC -v; echo '--'; exit 1";
+            };
+            testGcc = nixpkgs.stdenv.mkDerivation {
+                name = "testGcc";
+                unpackPhase = "NIX_DEBUG=1 $CC --version; echo $CC; $CC -v; exit 1";
+            };
+            inherit myenv;
+        };
 }
diff --git a/system.nix b/system.nix
index 45a7f1d..dff53c5 100644
--- a/system.nix
+++ b/system.nix
@@ -1,11 +1,11 @@
-{ pkgs }:
+{ pkgs, currentSystem }:
 let
-    parsedSystem = builtins.split "-" builtins.currentSystem;
+    parsedSystem = builtins.split "-" currentSystem;
     arch = builtins.head (parsedSystem);
     os = builtins.elemAt (parsedSystem) 2;
 
     system = pkgs.lib.systems.elaborate {
-        system = builtins.currentSystem;
+        system = currentSystem;
         config = "${arch}-unknown-linux-musl";
         isStatic = true;
         useLLVM = true;
diff --git a/test-stdenv.nix b/test-stdenv.nix
new file mode 100644
index 0000000..c634d43
--- /dev/null
+++ b/test-stdenv.nix
@@ -0,0 +1,22 @@
+{}:
+let
+    currentSystem = "x86_64-linux";
+    getNixPkgs = args: import ../nixpkgs args;
+
+    nixpkgs = getNixPkgs { system = currentSystem; };
+    system = import ./system.nix {
+        pkgs = nixpkgs;
+        inherit currentSystem;
+    };
+
+    # replaceStdenv = { pkgs }:
+    #     let
+    #         llvm = pkgs.llvmPackages_16.override { stdenv = pkgs.llvmPackages_16.libcxxStdenv; };
+    #     in
+    #       llvm.libcxxStdenv;
+
+    createPkgSet = getNixPkgs system;
+
+in {
+    inherit createPkgSet;
+}