diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..20669d9
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,44 @@
+{
+  "nodes": {
+    "mozilla-overlay": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1638887313,
+        "narHash": "sha256-FMYV6rVtvSIfthgC1sK1xugh3y7muoQcvduMdriz4ag=",
+        "owner": "mozilla",
+        "repo": "nixpkgs-mozilla",
+        "rev": "7c1e8b1dd6ed0043fb4ee0b12b815256b0b9de6f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "mozilla",
+        "repo": "nixpkgs-mozilla",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1642961095,
+        "narHash": "sha256-RLatktZmvwFBOyqdoIk4qdS4OGKB7aKIvvs4ZP2L8D8=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "604c44137d97b5111be1ca5c0d97f6e24fbc5c2c",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-21.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "mozilla-overlay": "mozilla-overlay",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
index 94ad118..3156aba 100644
--- a/flake.nix
+++ b/flake.nix
@@ -9,124 +9,119 @@
       pkgs = import nixpkgs { system = "x86_64-linux"; overlays = [ (import mozilla-overlay) ]; };
       
       # ==== rustPlatform
-      let
-        rustManifest = pkgs.fetchurl {
-          url = "https://static.rust-lang.org/dist/2021-01-29/channel-rust-nightly.toml";
-          sha256 = "sha256-T0D0ypXA+nuH7o3AHCokzSBZAvQxvef4x9+XxO3aBao=";
+      rustManifest = pkgs.fetchurl {
+        url = "https://static.rust-lang.org/dist/2021-01-29/channel-rust-nightly.toml";
+        sha256 = "sha256-EZKgw89AH4vxaJpUHmIMzMW/80wAFQlfcxRoBD9nz0c=";
+      };
+      targets = [];
+      rustChannelOfTargets = _channel: _date: targets:
+        (pkgs.lib.rustLib.fromManifestFile rustManifest {
+          inherit (pkgs) stdenv lib fetchurl patchelf;
+          }).rust.override {
+          inherit targets;
+          extensions = ["rust-src"];
         };
-        targets = [];
-        rustChannelOfTargets = _channel: _date: targets:
-          (pkgs.lib.rustLib.fromManifestFile rustManifest {
-            inherit (pkgs) stdenv lib fetchurl patchelf;
-            }).rust.override {
-            inherit targets;
-            extensions = ["rust-src"];
-          };
-        rust = rustChannelOfTargets "nightly" null targets;
-      in
-        rustPlatform = pkgs.recurseIntoAttrs (pkgs.makeRustPlatform {
-          rustc = rust;
-          cargo = rust;
-        });
+      rust = rustChannelOfTargets "nightly" null targets;
+      rustPlatform = pkgs.recurseIntoAttrs (pkgs.makeRustPlatform {
+        rustc = rust;
+        cargo = rust;
+      });
       # ==== rustPlatform / gnutoolchain
-      gnutoolchain = {
-        let
-          gnu-platform = "arm-none-eabi";
+        gnu-platform = "arm-none-eabi";
 
-          binutils-pkg = { extraConfigureFlags ? [] }: pkgs.stdenv.mkDerivation rec {
-            basename = "binutils";
-            version = "2.30";
-            name = "${basename}-${gnu-platform}-${version}";
-            src = pkgs.fetchurl {
-              url = "https://ftp.gnu.org/gnu/binutils/binutils-${version}.tar.bz2";
-              sha256 = "028cklfqaab24glva1ks2aqa1zxa6w6xmc8q34zs1sb7h22dxspg";
-            };
-            configureFlags = [
-              "--enable-deterministic-archives"
-              "--target=${gnu-platform}"
-              "--with-cpu=cortex-a9"
-              "--with-fpu=vfpv3"
-              "--with-float=hard"
-              "--with-mode=thumb"
-            ] ++ extraConfigureFlags;
-            outputs = [ "out" "info" "man" ];
-            depsBuildBuild = [ pkgs.buildPackages.stdenv.cc ];
-            buildInputs = [ pkgs.lib.zlib ];
-            enableParallelBuilding = true;
-            meta = {
-              description = "Tools for manipulating binaries (linker, assembler, etc.)";
-              longDescription = ''
-                The GNU Binutils are a collection of binary tools.  The main
-                ones are `ld' (the GNU linker) and `as' (the GNU assembler).
-                They also include the BFD (Binary File Descriptor) library,
-                `gprof', `nm', `strip', etc.
-              '';
-              homepage = http://www.gnu.org/software/binutils/;
-              license = pkgs.lib.licenses.gpl3Plus;
-              /* Give binutils a lower priority than gcc-wrapper to prevent a
-                collision due to the ld/as wrappers/symlinks in the latter. */
-              priority = "10";
-            };
+        binutils-pkg = { extraConfigureFlags ? [] }: pkgs.stdenv.mkDerivation rec {
+          basename = "binutils";
+          version = "2.30";
+          name = "${basename}-${gnu-platform}-${version}";
+          src = pkgs.fetchurl {
+            url = "https://ftp.gnu.org/gnu/binutils/binutils-${version}.tar.bz2";
+            sha256 = "028cklfqaab24glva1ks2aqa1zxa6w6xmc8q34zs1sb7h22dxspg";
           };
-
-          gcc-pkg = { platform-binutils, extraConfigureFlags ? [] }: pkgs.stdenv.mkDerivation rec {
-            basename = "gcc";
-            version = "9.1.0";
-            name = "${basename}-${gnu-platform}-${version}";
-            src = pkgs.fetchurl {
-              url = "https://ftp.gnu.org/gnu/gcc/gcc-${version}/gcc-${version}.tar.xz";
-              sha256 = "1817nc2bqdc251k0lpc51cimna7v68xjrnvqzvc50q3ax4s6i9kr";
-            };
-            preConfigure =
-            ''
-              mkdir build
-              cd build
+          configureFlags = [
+            "--enable-deterministic-archives"
+            "--target=${gnu-platform}"
+            "--with-cpu=cortex-a9"
+            "--with-fpu=vfpv3"
+            "--with-float=hard"
+            "--with-mode=thumb"
+          ] ++ extraConfigureFlags;
+          outputs = [ "out" "info" "man" ];
+          depsBuildBuild = [ pkgs.buildPackages.stdenv.cc ];
+          buildInputs = [ pkgs.lib.zlib ];
+          enableParallelBuilding = true;
+          meta = {
+            description = "Tools for manipulating binaries (linker, assembler, etc.)";
+            longDescription = ''
+              The GNU Binutils are a collection of binary tools.  The main
+              ones are `ld' (the GNU linker) and `as' (the GNU assembler).
+              They also include the BFD (Binary File Descriptor) library,
+              `gprof', `nm', `strip', etc.
             '';
-            configureScript = "../configure";
-            configureFlags =
-              [ "--target=${gnu-platform}"
-                "--with-arch=armv7-a"
-                "--with-tune=cortex-a9"
-                "--with-fpu=vfpv3"
-                "--with-float=hard"
-                "--disable-libssp"
-                "--enable-languages=c"
-                "--with-as=${platform-binutils}/bin/${gnu-platform}-as"
-                "--with-ld=${platform-binutils}/bin/${gnu-platform}-ld" ] ++ extraConfigureFlags;
-            outputs = [ "out" "info" "man" ];
-            hardeningDisable = [ "format" "pie" ];
-            propagatedBuildInputs = with pkgs.libs [ gmp mpfr libmpc platform-binutils ];
-            enableParallelBuilding = true;
-            dontFixup = true;
+            homepage = http://www.gnu.org/software/binutils/;
+            license = pkgs.lib.licenses.gpl3Plus;
+            /* Give binutils a lower priority than gcc-wrapper to prevent a
+              collision due to the ld/as wrappers/symlinks in the latter. */
+            priority = "10";
           };
+        };
 
-          newlib-pkg = { platform-binutils, platform-gcc }: pkgs.stdenv.mkDerivation rec {
-            pname = "newlib";
-            version = "3.1.0";
-            src = pkgs.fetchurl {
-              url = "ftp://sourceware.org/pub/newlib/newlib-${version}.tar.gz";
-              sha256 = "0ahh3n079zjp7d9wynggwrnrs27440aac04340chf1p9476a2kzv";
-            };
-            nativeBuildInputs = [ platform-binutils pkgs.platform-gcc ];
-            configureFlags = [
-              "--target=${gnu-platform}"
-
-              "--with-cpu=cortex-a9"
-              "--with-fpu=vfpv3"
-              "--with-float=hard"
-              "--with-mode=thumb"
-              "--enable-interwork"
-              "--disable-multilib"
-
-              "--disable-newlib-supplied-syscalls"
-              "--with-gnu-ld"
-              "--with-gnu-as"
-              "--disable-newlib-io-float"
-              "--disable-werror"
-            ];
-            dontFixup = true;
+        gcc-pkg = { platform-binutils, extraConfigureFlags ? [] }: pkgs.stdenv.mkDerivation rec {
+          basename = "gcc";
+          version = "9.1.0";
+          name = "${basename}-${gnu-platform}-${version}";
+          src = pkgs.fetchurl {
+            url = "https://ftp.gnu.org/gnu/gcc/gcc-${version}/gcc-${version}.tar.xz";
+            sha256 = "1817nc2bqdc251k0lpc51cimna7v68xjrnvqzvc50q3ax4s6i9kr";
           };
-        in rec {
+          preConfigure = ''
+            mkdir build
+            cd build
+          '';
+          configureScript = "../configure";
+          configureFlags = [ 
+            "--target=${gnu-platform}"
+            "--with-arch=armv7-a"
+            "--with-tune=cortex-a9"
+            "--with-fpu=vfpv3"
+            "--with-float=hard"
+            "--disable-libssp"
+            "--enable-languages=c"
+            "--with-as=${platform-binutils}/bin/${gnu-platform}-as"
+            "--with-ld=${platform-binutils}/bin/${gnu-platform}-ld" ] ++ extraConfigureFlags;
+          outputs = [ "out" "info" "man" ];
+          hardeningDisable = [ "format" "pie" ];
+          propagatedBuildInputs = with pkgs.libs; [ gmp mpfr libmpc platform-binutils ];
+          enableParallelBuilding = true;
+          dontFixup = true;
+        };
+
+        newlib-pkg = { platform-binutils, platform-gcc }: pkgs.stdenv.mkDerivation rec {
+          pname = "newlib";
+          version = "3.1.0";
+          src = pkgs.fetchurl {
+            url = "ftp://sourceware.org/pub/newlib/newlib-${version}.tar.gz";
+            sha256 = "0ahh3n079zjp7d9wynggwrnrs27440aac04340chf1p9476a2kzv";
+          };
+          nativeBuildInputs = [ platform-binutils pkgs.platform-gcc ];
+          configureFlags = [
+            "--target=${gnu-platform}"
+
+            "--with-cpu=cortex-a9"
+            "--with-fpu=vfpv3"
+            "--with-float=hard"
+            "--with-mode=thumb"
+            "--enable-interwork"
+            "--disable-multilib"
+
+            "--disable-newlib-supplied-syscalls"
+            "--with-gnu-ld"
+            "--with-gnu-as"
+            "--disable-newlib-io-float"
+            "--disable-werror"
+          ];
+          dontFixup = true;
+        };
+        gnutoolchain = rec {
           binutils-bootstrap = pkgs.callPackage binutils-pkg { };
           gcc-bootstrap = pkgs.callPackage gcc-pkg {
             platform-binutils = binutils-bootstrap;
@@ -143,8 +138,7 @@
             platform-binutils = binutils;
             extraConfigureFlags = [ "--enable-newlib" "--with-headers=${newlib}/arm-none-eabi/include" ];
           };
-        }
-      }
+        };
       # ==== gnutoolchain/cargo-xbuild
       cargo-xbuild = rustPlatform.buildRustPackage rec {
         pname = "cargo-xbuild";
@@ -156,16 +150,15 @@
           rev = "v${version}";
           sha256 = "18djvygq9v8rmfchvi2hfj0i6fhn36m716vqndqnj56fiqviwxvf";
         };
-        cargoLock = {
-          lockFile = [ ./Cargo.lock ]
-        }
+        cargoSha256 = "13sj9j9kl6js75h9xq0yidxy63vixxm9q3f8jil6ymarml5wkhx8";
+        
         meta = with pkgs.lib; {
           description = "Automatically cross-compiles the sysroot crates core, compiler_builtins, and alloc";
           homepage = "https://github.com/rust-osdev/cargo-xbuild";
           license = with licenses; [ mit asl20 ];
           maintainers = with maintainers; [ johntitor xrelkd ];
         };
-      }
+      };
       # ==== cargo-xbuild/mkbootimage
       mkbootimage = pkgs.stdenv.mkDerivation {
         pname = "mkbootimage";
@@ -188,7 +181,7 @@
           mkdir -p $out/bin
           cp mkbootimage $out/bin
         '';
-      }
+      };
       # ==== mkbootimage/fsbl
       fsbl = { board ? "zc706" }: pkgs.stdenv.mkDerivation {
         name = "${board}-fsbl";
@@ -219,7 +212,7 @@
         '';
         doCheck = false;
         dontFixup = true;
-      }
+      };
     # ==== fsbl/
     in {
       packages.x86_64-linux = {
@@ -241,8 +234,8 @@
           openocd gdb
           openssh rsync
           llvmPackages_9.clang-unwrapped
-          mkbootimage
+          mkbootimage ];
         };
-      defaultPackage.x86_64-linux = zynq-rs;
+      defaultPackage.x86_64-linux = fsbl { board = "zc706"; };
     };
 }
\ No newline at end of file