diff --git a/.github/workflows/push.yml b/.github/workflows/push.yml
index f732856..45b9bd5 100644
--- a/.github/workflows/push.yml
+++ b/.github/workflows/push.yml
@@ -1,13 +1,38 @@
-on: [pull_request]
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+      - ready_for_review
+      - labeled
 jobs:
-  checks:
+  build-and-test:
+    name: "Build and Test"
     runs-on: ubuntu-latest
-    container: archlinux/archlinux:latest
     steps:
+      - uses: cachix/install-nix-action@v27
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
       - name: Install dependencies
-        run: pacman -Syu --noconfirm make mill z3
-      - uses: actions/checkout@v2
-      - name: Check Format
-        run: make checkformat
+        run: nix-env -i mill verilator z3 -f '<nixpkgs>'
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: Test
         run: make test
+
+  check-format:
+    name: "Check Format"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: cachix/install-nix-action@v27
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - name: Install dependencies
+        run: nix-env -i mill -f '<nixpkgs>'
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Test
+        run: make checkformat
diff --git a/.gitignore b/.gitignore
index a507599..a75eb83 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,11 +10,12 @@
 !*.cc
 !.gitignore
 !.scalafmt.conf
-!build.sc
 !README.md
 build/
 
 # mill
+!*.mill
+!.mill-version
 out/
 .bsp/
 .idea/
diff --git a/.mill-version b/.mill-version
new file mode 100644
index 0000000..e2e3067
--- /dev/null
+++ b/.mill-version
@@ -0,0 +1 @@
+0.12.7
diff --git a/build.sc b/build.mill
similarity index 95%
rename from build.sc
rename to build.mill
index 6a61ab7..38595ca 100644
--- a/build.sc
+++ b/build.mill
@@ -1,3 +1,5 @@
+package build
+
 // import Mill dependency
 import mill._
 import mill.define.Sources
@@ -29,7 +31,7 @@ object playground extends ScalaModule with ScalafmtModule { m =>
     )
   }
 
-  def repositoriesTask = T.task {
+  def repositoriesTask = Task.Anon {
     Seq(
       coursier.MavenRepository("https://repo.scala-sbt.org/scalasbt/maven-releases"),
       coursier.MavenRepository("https://oss.sonatype.org/content/repositories/releases"),