diff --git a/flake.lock b/flake.lock
index 1c8e62bd82..e66c04991a 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1776683584,
-        "narHash": "sha256-NuTLMrr10Tng72hurYG8jYQ4XKK8wnpJmOGcPiis96g=",
+        "lastModified": 1777270315,
+        "narHash": "sha256-yKB4G6cKsQsWN7M6rZGk6gkJPDNPIzT05y4qzRyCDlI=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "9dd5558b06dbdacbf635a3dd36dce1b1a7ee3a89",
+        "rev": "6368eda62c9775c38ef7f714b2555a741c20c72d",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 13293523aa..6380c23d27 100644
--- a/flake.nix
+++ b/flake.nix
@@ -21,9 +21,63 @@
       devShells = forEachSystem (pkgs: {
         default =
           let
+            # Pin bun to the version declared in package.json (packageManager: "bun@1.3.13").
+            # nixpkgs-unstable currently ships 1.3.11, so we fetch the official release directly.
+            bun =
+              let
+                sources = {
+                  "aarch64-linux" = {
+                    name = "bun-linux-aarch64";
+                    hash = "sha256-cLrkGzkIsKEg4eWMXIrzDnSvrjuNEbDT/djnh937SyI=";
+                  };
+                  "x86_64-linux" = {
+                    name = "bun-linux-x64";
+                    hash = "sha256-ecB3H6i5LDOq5B4VoODTB+qZ0OLwAxfHHGxTI3p44lo=";
+                  };
+                  "aarch64-darwin" = {
+                    name = "bun-darwin-aarch64";
+                    hash = "sha256-VGfj9l26Umuf6pjwzOBO+vwMY+Fpcz7Ce4dqOtMtoZA=";
+                  };
+                  "x86_64-darwin" = {
+                    name = "bun-darwin-x64";
+                    hash = "sha256-5abItk9BmSUjLREeyxPiXwq/VeVPeSNB+YdiP9B3gAk=";
+                  };
+                };
+                source =
+                  sources.${pkgs.stdenv.hostPlatform.system}
+                    or (throw "Unsupported system for bun: ${pkgs.stdenv.hostPlatform.system}");
+              in
+              pkgs.stdenv.mkDerivation rec {
+                pname = "bun";
+                version = "1.3.13";
+                src = pkgs.fetchurl {
+                  url = "https://github.com/oven-sh/bun/releases/download/bun-v${version}/${source.name}.zip";
+                  inherit (source) hash;
+                };
+                nativeBuildInputs = [
+                  pkgs.unzip
+                ] ++ pkgs.lib.optional pkgs.stdenv.isLinux pkgs.autoPatchelfHook;
+                buildInputs = pkgs.lib.optionals pkgs.stdenv.isLinux [ pkgs.stdenv.cc.cc.lib ];
+                dontConfigure = true;
+                dontBuild = true;
+                installPhase = ''
+                  runHook preInstall
+                  install -Dm755 bun $out/bin/bun
+                  ln -s $out/bin/bun $out/bin/bunx
+                  runHook postInstall
+                '';
+                meta = {
+                  description = "Fast all-in-one JavaScript runtime";
+                  homepage = "https://bun.sh";
+                  license = pkgs.lib.licenses.mit;
+                  mainProgram = "bun";
+                  platforms = builtins.attrNames sources;
+                };
+              };
+
             kilo-dev = pkgs.writeShellScriptBin "kilo-dev" ''
                 cd "$KILO_ROOT"
-              exec ${pkgs.bun}/bin/bun dev "$@"
+              exec ${bun}/bin/bun dev "$@"
             '';
 
             kilo-install-bin = pkgs.writeShellScriptBin "kilo-install" ''