diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..a5dbbcb
--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+use flake .
diff --git a/flake.lock b/flake.lock
index 1100636..6868307 100644
--- a/flake.lock
+++ b/flake.lock
@@ -1,23 +1,5 @@
 {
   "nodes": {
-    "flake-utils": {
-      "inputs": {
-        "systems": "systems"
-      },
-      "locked": {
-        "lastModified": 1731533236,
-        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "type": "github"
-      }
-    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1754498491,
@@ -52,7 +34,6 @@
     },
     "root": {
       "inputs": {
-        "flake-utils": "flake-utils",
         "nixpkgs": "nixpkgs",
         "rust-overlay": "rust-overlay"
       }
@@ -74,21 +55,6 @@
         "repo": "rust-overlay",
         "type": "github"
       }
-    },
-    "systems": {
-      "locked": {
-        "lastModified": 1681028828,
-        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
-        "owner": "nix-systems",
-        "repo": "default",
-        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-systems",
-        "repo": "default",
-        "type": "github"
-      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index eb90221..643f630 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,36 +1,37 @@
 {
-  description = "Rust Development Shell";
+  description = "Pinned Rust dev shell";
 
   inputs = {
-    nixpkgs.url      = "github:NixOS/nixpkgs/nixos-unstable";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     rust-overlay.url = "github:oxalica/rust-overlay";
-    flake-utils.url  = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, rust-overlay, flake-utils, ... }:
-    flake-utils.lib.eachDefaultSystem (system:
+  outputs = { self, nixpkgs, rust-overlay, ... }:
+  let
+    systems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+    forAllSystems = f: nixpkgs.lib.genAttrs systems (system:
       let
-        overlays = [ (import rust-overlay) ];
         pkgs = import nixpkgs {
-          inherit system overlays;
+          inherit system;
+          overlays = [ (import rust-overlay) ];
         };
-      in
-      with pkgs;
-      {
-        devShells.default = mkShell {
-          buildInputs = [
-            openssl
-            pkg-config
-            (
-              rust-bin.selectLatestNightlyWith (toolchain: toolchain.default.override {
-                extensions = [
-                  "rust-src"
-                  "rust-analyzer"
-                ];
-              })
-            )
-          ];
+        rustToolchain = pkgs.rust-bin.stable."1.89.0".default.override {
+          extensions = [ "rust-src" "rust-analyzer" ];
         };
-      }
+      in f pkgs rustToolchain
     );
+  in {
+    devShells = forAllSystems (pkgs: rustToolchain: {
+      default = pkgs.mkShell {
+        nativeBuildInputs = [
+          pkgs.pkg-config
+          rustToolchain
+          pkgs.lldb
+        ];
+        buildInputs = [
+          pkgs.openssl
+        ];
+      };
+    });
+  };
 }
diff --git a/flake_old.nix b/flake_old.nix
new file mode 100644
index 0000000..eb90221
--- /dev/null
+++ b/flake_old.nix
@@ -0,0 +1,36 @@
+{
+  description = "Rust Development Shell";
+
+  inputs = {
+    nixpkgs.url      = "github:NixOS/nixpkgs/nixos-unstable";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    flake-utils.url  = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, rust-overlay, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        overlays = [ (import rust-overlay) ];
+        pkgs = import nixpkgs {
+          inherit system overlays;
+        };
+      in
+      with pkgs;
+      {
+        devShells.default = mkShell {
+          buildInputs = [
+            openssl
+            pkg-config
+            (
+              rust-bin.selectLatestNightlyWith (toolchain: toolchain.default.override {
+                extensions = [
+                  "rust-src"
+                  "rust-analyzer"
+                ];
+              })
+            )
+          ];
+        };
+      }
+    );
+}