diff --git a/.github/workflows/package.yml b/.github/workflows/package.yml
index a512199..21640d0 100644
--- a/.github/workflows/package.yml
+++ b/.github/workflows/package.yml
@@ -104,3 +104,15 @@ jobs:
         with:
           file: "${{ github.workspace }}/out/rpm_package/*.rpm;${{ github.workspace }}/out/rpm_package/*.rpm.sha512"
           tags: true
+
+  nix:
+    name: Build nix package
+    runs-on: ubuntu-22.04
+    needs: metadata
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 #v4.2.2
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@3715ab1a11cac9e991980d7b4a28d80c7ebdd8f9 # v28
+      - name: Build
+        run: nix-build ${{ github.workspace }}/tools/nix -A filc
diff --git a/.gitignore b/.gitignore
index 299cea8..5470fcb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@ filc
 !include/*
 !src/*
 out
+result
 !bin/*
 coverage.info
 .idea
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 75b99ae..835d70c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,7 +19,7 @@ file(READ ${CMAKE_CURRENT_SOURCE_DIR}/VERSION FILC_VERSION)
 project(
         filc
         VERSION ${FILC_VERSION}
-        LANGUAGES C CXX
+        LANGUAGES CXX
 )
 
 include(FetchContent)
diff --git a/shell.nix b/shell.nix
index b6b6413..33c306f 100644
--- a/shell.nix
+++ b/shell.nix
@@ -3,8 +3,7 @@
 let
   currentDir = builtins.toString ./.;
   pnpm = pkgs.callPackage ./tools/nix/pnpm.nix { nodejs = pkgs.nodejs_20; };
-  cxxopts = pkgs.callPackage ./tools/nix/cxxopts.nix { };
-  antlr4 = pkgs.callPackage ./tools/nix/antlr4.nix { };
+  cxxopts = pkgs.cxxopts.override { enableUnicodeHelp = false; };
 in
 
 pkgs.mkShell {
@@ -27,8 +26,8 @@ pkgs.mkShell {
     pkgs.libffi
     pkgs.libxml2
     cxxopts
-    antlr4.antlr
-    antlr4.runtime.cpp
+    pkgs.antlr4_13
+    pkgs.antlr4_13.runtime.cpp
   ];
 
   shellHook = ''
diff --git a/tools/nix/antlr4.nix b/tools/nix/antlr4.nix
deleted file mode 100644
index 19924cf..0000000
--- a/tools/nix/antlr4.nix
+++ /dev/null
@@ -1,78 +0,0 @@
-{ stdenv
-, fetchurl
-, fetchFromGitHub
-, jre
-, cmake, ninja, pkg-config
-}:
-
-# From https://github.com/NixOS/nixpkgs/blob/nixos-24.11/pkgs/development/tools/parsing/antlr/4.nix
-let
-  mkAntlr = {
-    version, jarHash, srcHash
-  }: rec {
-    antlr = stdenv.mkDerivation {
-      pname = "antlr";
-      inherit version;
-
-      src = fetchurl {
-        url = "https://www.antlr.org/download/antlr-${version}-complete.jar";
-        hash = jarHash;
-      };
-
-      dontUnpack = true;
-
-      installPhase = ''
-        mkdir -p "$out"/{share/java,bin}
-        ln -s "$src" "$out/share/java/antlr-${version}-complete.jar"
-
-        echo "#! ${stdenv.shell}" >> "$out/bin/antlr"
-        echo "'${jre}/bin/java' -cp '$out/share/java/antlr-${version}-complete.jar:$CLASSPATH' -Xmx500M org.antlr.v4.Tool \"\$@\"" >> "$out/bin/antlr"
-
-        echo "#! ${stdenv.shell}" >> "$out/bin/antlr-parse"
-        echo "'${jre}/bin/java' -cp '$out/share/java/antlr-${version}-complete.jar:$CLASSPATH' -Xmx500M org.antlr.v4.gui.Interpreter \"\$@\"" >> "$out/bin/antlr-parse"
-
-        echo "#! ${stdenv.shell}" >> "$out/bin/grun"
-        echo "'${jre}/bin/java' -cp '$out/share/java/antlr-${version}-complete.jar:$CLASSPATH' org.antlr.v4.gui.TestRig \"\$@\"" >> "$out/bin/grun"
-
-        chmod a+x "$out/bin/antlr" "$out/bin/antlr-parse" "$out/bin/grun"
-        ln -s "$out/bin/antlr"{,4}
-        ln -s "$out/bin/antlr"{,4}-parse
-      '';
-
-      inherit jre;
-
-      passthru = {
-        inherit runtime;
-        jarLocation = antlr.src;
-      };
-    };
-
-    runtime.cpp = stdenv.mkDerivation {
-      pname = "antlr-runtime-cpp";
-      inherit version;
-
-      src = fetchFromGitHub {
-        owner = "antlr";
-        repo = "antlr4";
-        rev = version;
-        hash = srcHash;
-      };
-
-      outputs = [ "out" "dev" "doc" ];
-
-      nativeBuildInputs = [ cmake ninja pkg-config ];
-
-      cmakeDir = "../runtime/Cpp";
-      cmakeFlags = [
-        "-DANTLR4_INSTALL=ON"
-        "-DANTLR_BUILD_CPP_TESTS=OFF"
-      ];
-    };
-  };
-in
-
-mkAntlr {
-  version = "4.13.0";
-  jarHash = "sha256-vG9KvA0iWidXASbFFAJWnwAKje2jSHtw52QoQOVw5KY=";
-  srcHash = "sha256-s1yAdScMYg1wFpYNsBAtpifIhQsnSAgJg7JjPDx+htc=";
-}
diff --git a/tools/nix/cxxopts.nix b/tools/nix/cxxopts.nix
deleted file mode 100644
index 36f0a91..0000000
--- a/tools/nix/cxxopts.nix
+++ /dev/null
@@ -1,33 +0,0 @@
-{ stdenv
-, fetchFromGitHub
-, icu
-, cmake, pkg-config
-}:
-
-# From https://github.com/NixOS/nixpkgs/blob/nixos-24.11/pkgs/by-name/cx/cxxopts/package.nix
-stdenv.mkDerivation rec {
-  pname = "cxxopts";
-  version = "3.2.0";
-
-  src = fetchFromGitHub {
-    owner = "jarro2783";
-    repo = "cxxopts";
-    rev = "v${version}";
-    hash = "sha256-tOO0YCIG3MxSJZhurNcDR1pWIUEO/Har9mrCrZs3iVk=";
-  };
-
-#  buildInputs = [ icu.dev ];
-  cmakeFlags = [
-    "-DCXXOPTS_BUILD_EXAMPLES=OFF"
-    "-DCXXOPTS_USE_UNICODE_HELP=FALSE"
-  ];
-  nativeBuildInputs = [ cmake pkg-config ];
-
-  doCheck = true;
-  dontUserCmakeBuildDir = true;
-
-  postPatch = ''
-    substituteInPlace packaging/pkgconfig.pc.in \
-      --replace '$'{prefix}/@CMAKE_INSTALL_INCLUDEDIR@ @CMAKE_INSTALL_FULL_INCLUDEDIR@
-  '';
-}
diff --git a/tools/nix/default.nix b/tools/nix/default.nix
new file mode 100644
index 0000000..608d77b
--- /dev/null
+++ b/tools/nix/default.nix
@@ -0,0 +1,5 @@
+let
+  pkgs = import ./pin-nixpkgs.nix { };
+in {
+  filc = pkgs.callPackage ./filc.nix { };
+}
diff --git a/tools/nix/filc.nix b/tools/nix/filc.nix
new file mode 100644
index 0000000..0a9875b
--- /dev/null
+++ b/tools/nix/filc.nix
@@ -0,0 +1,28 @@
+{ stdenvNoCC
+, fetchFromGitHub
+, cmake
+, ninja
+, clang
+, cxxopts
+, antlr4_13
+, llvmPackages_18
+}:
+
+let
+  cxxopts_filc = cxxopts.override { enableUnicodeHelp = false; };
+in
+
+stdenvNoCC.mkDerivation rec {
+  pname = "filc";
+  version = "0.1.0";
+
+  src = fetchFromGitHub {
+    owner = "Fil-Language";
+    repo = "filc";
+    rev = "v${version}";
+    hash = "sha256-MB6ABwxVYdJ4YxLHKNvDLrFUN6M/u2/vk1+x3rjktPU=";
+  };
+
+  nativeBuildInputs = [ cmake ninja clang ];
+  buildInputs = [ cxxopts_filc antlr4_13 antlr4_13.runtime.cpp llvmPackages_18.libllvm ];
+}