diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..7212f3c
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,17 @@
+name: "Check"
+on:
+  pull_request:
+# cancel previous runs when pushing new changes
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+jobs:
+  checks:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: cachix/install-nix-action@v22
+      with:
+        extra_nix_config: "system-features = kvm nixos-test"
+    - run: nix flake check -L --keep-going
+    - run: nix flake check -L --keep-going ./example
diff --git a/.gitignore b/.gitignore
index 0309149..7c9dbce 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
-/example/result
+result-*
+result
+.direnv
diff --git a/example/home.nix b/example/home.nix
index cbeeb4c..2f28e07 100644
--- a/example/home.nix
+++ b/example/home.nix
@@ -1,4 +1,4 @@
-{ ... }:
+{ pkgs, ... }:
 {
   programs.plasma = {
     enable = true;
diff --git a/script/write_config.py b/script/write_config.py
index 00af706..b4dbb22 100644
--- a/script/write_config.py
+++ b/script/write_config.py
@@ -3,7 +3,7 @@ import json
 import os
 import re
 import sys
-from typing import Dict
+from typing import Dict, Optional
 
 
 class KConfParser:
@@ -89,7 +89,7 @@ class KConfParser:
                     f.write(f"{self.key_value_to_line(key, value)}\n")
 
     @staticmethod
-    def get_key_value(line: str) -> tuple[str, str | None]:
+    def get_key_value(line: str) -> tuple[str, Optional[str]]:
         line_splitted = line.split("=", 1)
         key = line_splitted[0].strip()
         value = line_splitted[1].strip() if len(line_splitted) > 1 else None