diff --git a/.github/workflows/checkfmt.yml b/.github/workflows/checkfmt.yml
new file mode 100644
index 0000000..077ec5d
--- /dev/null
+++ b/.github/workflows/checkfmt.yml
@@ -0,0 +1,46 @@
+name: Check the format of a PR
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+      - ready_for_review
+      - labeled
+env:
+  USER: runner
+
+# Cancel the current workflow when new commit pushed
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+
+  check-format:
+    name: "Check format"
+    runs-on: [self-hosted, linux, nixos]
+    strategy:
+      fail-fast: false
+    defaults:
+      run:
+        working-directory: ./templates/chisel
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: "Check Scala format"
+        continue-on-error: true
+        run: |
+          nix develop -c bash -c 'mill -i gcd.checkFormat && mill -i elaborator.checkFormat'
+      - name: "Check Rust format"
+        continue-on-error: true
+        run: |
+          cd gcdemu
+          nix develop -c cargo fmt --check
+          cd ..
+      - name: "Check nix format"
+        continue-on-error: true
+        run: |
+          nix fmt -- --check nix flake.nix
+
diff --git a/.github/workflows/daily-bump.yml b/.github/workflows/daily-bump.yml
new file mode 100644
index 0000000..2424efb
--- /dev/null
+++ b/.github/workflows/daily-bump.yml
@@ -0,0 +1,66 @@
+name: Dependencies Bump
+on:
+  schedule:
+    # Run this job everyday at 5:30 AM UTC+8
+    - cron:  '30 21 * * *'
+
+jobs:
+  bump-deps:
+    name: "Bump Chisel and CIRCT"
+    if: ${{ !cancelled() }}
+    runs-on: [self-hosted, linux, nixos]
+    permissions:
+      contents: write
+    defaults:
+      run:
+        working-directory: ./templates/chisel
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          ref: master
+      - name: Bump nixpkgs
+        run: |
+          nix flake update 
+      - name: Bump Chisel
+        run: |
+          cd nix/pkgs/dependencies
+          nix run '.#nvfetcher' -- -f '^chisel$'
+      - name: Bump all mill deps
+        run: |
+          oldHash=$(nix derivation show .#gcd.gcd-compiled.millDeps | jq -r 'to_entries[0].value.env.outputHash')
+          nix build '.#gcd.gcd-compiled.millDeps' --rebuild > milldeps-log.txt 2>&1 || true
+          newHash=$(cat milldeps-log.txt \
+            | grep -P '^\s+got:\s+sha256-.*$' \
+            | cut -d':' -f2 \
+            | xargs)
+          if [ -z "$newHash" ] || [ "$newHash" = "$oldHash" ]; then
+            echo "Original build logs for debug: "
+            cat milldeps-log.txt
+            echo "Hash unchanged, exit"
+            exit 0
+          fi
+          echo "Updating hash $oldHash to $newHash"
+          sed -i "s|$oldHash|$newHash|" nix/gcd/gcd.nix
+      - name: Commit changes
+        env:
+          GITHUB_TOKEN: ${{ secrets.BIYUN_GITHUB_ACTION }}
+        run: |
+          git config user.name github-actions[bot]
+          git config user.email 41898282+github-actions[bot]@users.noreply.github.com
+
+          currentDate=$(date +%F)
+          branch="dependencies-bumping-$currentDate"
+          git checkout -b "$branch"
+
+          git add 'nix/pkgs/dependencies'
+          git add 'flake.lock'
+
+          if ! git diff --quiet --cached --exit-code; then
+            updatedFiles=$(git diff --cached --name-only)
+            echo "File changed"
+            git commit -m "[deps] Bump dependencies"
+            git push origin "$branch" --force-with-lease
+            nix run '.#gh' -- \
+              pr create --title "Bump dependencies" --body "Updated: $updatedFiles"
+          fi
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 0000000..134810b
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,75 @@
+name: Build and Run Simulation
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+      - ready_for_review
+      - labeled
+env:
+  USER: runner
+
+# Cancel the current workflow when new commit pushed
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+
+  build-simulators:
+    name: "Build Simulators"
+    runs-on: [self-hosted, linux, nixos, BIGRAM]
+    strategy:
+      fail-fast: false
+    defaults:
+      run:
+        working-directory: ./templates/chisel
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: "Build vcs simulator"
+        run: |
+          nix build '.#gcd.vcs' --impure
+      - name: "Build vcs simulator with trace"
+        run: |
+          nix build '.#gcd.vcs-trace' --impure
+      - name: "Build verilator simulator"
+        run: |
+          nix build '.#gcd.verilated'
+      - name: "Build verilator simulator with trace"
+        run: |
+          nix build '.#gcd.verilated-trace'
+
+  run-vcs:
+    name: "Run VCS"
+    strategy:
+      fail-fast: false
+    runs-on: [self-hosted, linux, nixos]
+    defaults:
+      run:
+        working-directory: ./templates/chisel
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: "Run VCS"
+        run: |
+          nix build '.#gcd.vcs.tests.simple-sim' --impure -L
+
+  run-verilator:
+    name: "Run Verilator"
+    strategy:
+      fail-fast: false
+    runs-on: [self-hosted, linux, nixos]
+    defaults:
+      run:
+        working-directory: ./templates/chisel
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: "Run verilator"
+        run: |
+          nix run '.#gcd.verilated'
diff --git a/templates/chisel/.gitignore b/templates/chisel/.gitignore
index f373a7b..338f9fc 100644
--- a/templates/chisel/.gitignore
+++ b/templates/chisel/.gitignore
@@ -1,7 +1,17 @@
 .bloop
+.bsp
+.jvm-opts
+.mill-jvm-opts
 .metals/
 .vscode/
+
 out/
 result*
+gcd-sim-result/
 /dependencies/
 target/
+
+*.vcd
+*.fst
+*.fsdb
+*.log
diff --git a/templates/chisel/.scalafmt.conf b/templates/chisel/.scalafmt.conf
index c839f64..0310aaa 100644
--- a/templates/chisel/.scalafmt.conf
+++ b/templates/chisel/.scalafmt.conf
@@ -10,7 +10,7 @@ lineEndings = preserve
 includeCurlyBraceInSelectChains = false
 danglingParentheses.preset = true
 
-align.tokens.add = [
+align.tokens."+" = [
 {
   code = ":"
 }
diff --git a/templates/chisel/build.sc b/templates/chisel/build.sc
index 4da6ed7..3b79023 100644
--- a/templates/chisel/build.sc
+++ b/templates/chisel/build.sc
@@ -37,7 +37,7 @@ trait GCD extends millbuild.common.HasChisel with ScalafmtModule {
 }
 
 object elaborator extends Elaborator
-trait Elaborator extends millbuild.common.ElaboratorModule {
+trait Elaborator extends millbuild.common.ElaboratorModule with ScalafmtModule {
   def scalaVersion = T(deps.scalaVer)
 
   def panamaconverterModule = panamaconverter
diff --git a/templates/chisel/configs/GCDTestBenchMain.json b/templates/chisel/configs/GCDTestBenchMain.json
index c6ee49f..2daa26b 100644
--- a/templates/chisel/configs/GCDTestBenchMain.json
+++ b/templates/chisel/configs/GCDTestBenchMain.json
@@ -10,6 +10,6 @@
         "width": 16,
         "useAsyncReset": false
     },
-    "timeout": 5000,
+    "timeout": 70000,
     "testSize": 100
 }
diff --git a/templates/chisel/elaborator/src/GCD.scala b/templates/chisel/elaborator/src/GCD.scala
index c0959f9..fb92fdc 100644
--- a/templates/chisel/elaborator/src/GCD.scala
+++ b/templates/chisel/elaborator/src/GCD.scala
@@ -11,6 +11,8 @@ object GCDMain extends Elaborator {
   case class GCDParameterMain(
     @arg(name = "xLen") xLen:                   Int,
     @arg(name = "useAsyncReset") useAsyncReset: Boolean) {
+    require(xLen > 0, "xLen must be a non-negative integer")
+    require(chisel3.util.isPow2(xLen), "xLen must be a power of 2")
     def convert: GCDParameter = GCDParameter(xLen, useAsyncReset)
   }
 
diff --git a/templates/chisel/flake.nix b/templates/chisel/flake.nix
index c796c60..db27558 100644
--- a/templates/chisel/flake.nix
+++ b/templates/chisel/flake.nix
@@ -20,7 +20,8 @@
           overlays = [ overlay ];
           inherit system;
         };
-      in {
+      in
+      {
         formatter = pkgs.nixpkgs-fmt;
         legacyPackages = pkgs;
         devShells.default = pkgs.mkShell ({
diff --git a/templates/chisel/gcdemu/src/drive.rs b/templates/chisel/gcdemu/src/drive.rs
index 700d6ed..98fe414 100644
--- a/templates/chisel/gcdemu/src/drive.rs
+++ b/templates/chisel/gcdemu/src/drive.rs
@@ -107,8 +107,8 @@ impl Driver {
             WATCHDOG_FINISH
         } else if tick - self.last_input_cycle > self.timeout {
             error!(
-                "[{}] watchdog timeout, last input tick = {}",
-                tick, self.last_input_cycle
+                "[{}] watchdog timeout, last input tick = {}, {} tests completed",
+                tick, self.last_input_cycle, self.test_num
             );
             WATCHDOG_TIMEOUT
         } else {
diff --git a/templates/chisel/nix/gcd/default.nix b/templates/chisel/nix/gcd/default.nix
index 947afc4..c4bc76f 100644
--- a/templates/chisel/nix/gcd/default.nix
+++ b/templates/chisel/nix/gcd/default.nix
@@ -3,56 +3,55 @@
 
 { lib, newScope, }:
 lib.makeScope newScope (scope:
-  let
-    designTarget = "GCD";
-    tbTarget = "GCDTestBench";
-    dpiLibName = "gcdemu";
-  in {
-    # RTL
-    gcd-compiled = scope.callPackage ./gcd.nix { target = designTarget; };
-    elaborate = scope.callPackage ./elaborate.nix {
-      elaborator = scope.gcd-compiled.elaborator;
-    };
-    mlirbc = scope.callPackage ./mlirbc.nix { };
-    rtl = scope.callPackage ./rtl.nix { };
+let
+  designTarget = "GCD";
+  tbTarget = "GCDTestBench";
+  dpiLibName = "gcdemu";
+in
+{
+  # RTL
+  gcd-compiled = scope.callPackage ./gcd.nix { target = designTarget; };
+  elaborate = scope.callPackage ./elaborate.nix {
+    elaborator = scope.gcd-compiled.elaborator;
+  };
+  mlirbc = scope.callPackage ./mlirbc.nix { };
+  rtl = scope.callPackage ./rtl.nix { };
 
-    # Testbench
-    tb-compiled = scope.callPackage ./gcd.nix { target = tbTarget; };
-    tb-elaborate = scope.callPackage ./elaborate.nix {
-      elaborator = scope.tb-compiled.elaborator;
-    };
-    tb-mlirbc =
-      scope.callPackage ./mlirbc.nix { elaborate = scope.tb-elaborate; };
-    tb-rtl = scope.callPackage ./rtl.nix { mlirbc = scope.tb-mlirbc; };
-    tb-dpi-lib = scope.callPackage ./dpi-lib.nix { inherit dpiLibName; };
+  # Testbench
+  tb-compiled = scope.callPackage ./gcd.nix { target = tbTarget; };
+  tb-elaborate = scope.callPackage ./elaborate.nix {
+    elaborator = scope.tb-compiled.elaborator;
+  };
+  tb-mlirbc =
+    scope.callPackage ./mlirbc.nix { elaborate = scope.tb-elaborate; };
+  tb-rtl = scope.callPackage ./rtl.nix { mlirbc = scope.tb-mlirbc; };
+  tb-dpi-lib = scope.callPackage ./dpi-lib.nix { inherit dpiLibName; };
 
-    verilated = scope.callPackage ./verilated.nix {
-      rtl = scope.tb-rtl.override { enable-layers = [ "Verification" ]; };
-      dpi-lib = scope.tb-dpi-lib;
-    };
-    verilated-trace = scope.verilated.override {
-      dpi-lib = scope.verilated.dpi-lib.override { enable-trace = true; };
-    };
-    vcs = scope.callPackage ./vcs.nix {
-      dpi-lib = scope.tb-dpi-lib.override {
-        sv2023 = false;
-        vpi = true;
-      };
-      rtl = scope.tb-rtl.override {
-        enable-layers =
-          [ "Verification" "Verification.Assert" "Verification.Cover" ];
-      };
+  verilated = scope.callPackage ./verilated.nix {
+    rtl = scope.tb-rtl.override { enable-layers = [ "Verification" ]; };
+    dpi-lib = scope.tb-dpi-lib;
+  };
+  verilated-trace = scope.verilated.override {
+    dpi-lib = scope.verilated.dpi-lib.override { enable-trace = true; };
+  };
+  vcs = scope.callPackage ./vcs.nix {
+    dpi-lib = scope.tb-dpi-lib.override {
+      sv2023 = false;
+      vpi = true;
+      timescale = 1000;
     };
-    vcs-trace = scope.vcs.override {
-      dpi-lib = scope.vcs.dpi-lib.override {
-        enable-trace = true;
-        timescale = 1000;
-      };
+    rtl = scope.tb-rtl.override {
+      enable-layers =
+        [ "Verification" "Verification.Assert" "Verification.Cover" ];
     };
+  };
+  vcs-trace = scope.vcs.override {
+    dpi-lib = scope.vcs.dpi-lib.override { enable-trace = true; };
+  };
 
-    # TODO: designConfig should be read from OM
-    tbConfig = with builtins;
-      fromJSON (readFile ./../../configs/${tbTarget}Main.json);
+  # TODO: designConfig should be read from OM
+  tbConfig = with builtins;
+    fromJSON (readFile ./../../configs/${tbTarget}Main.json);
 
-  })
+})
 
diff --git a/templates/chisel/nix/gcd/dpi-lib.nix b/templates/chisel/nix/gcd/dpi-lib.nix
index c388c82..b4dcb56 100644
--- a/templates/chisel/nix/gcd/dpi-lib.nix
+++ b/templates/chisel/nix/gcd/dpi-lib.nix
@@ -1,8 +1,15 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: 2024 Jiuyang Liu <liu@jiuyang.me>
 
-{ lib, rustPlatform, tbConfig, dpiLibName, sv2023 ? true, vpi ? false
-, enable-trace ? false, timescale ? 1 }:
+{ lib
+, rustPlatform
+, tbConfig
+, dpiLibName
+, sv2023 ? true
+, vpi ? false
+, enable-trace ? false
+, timescale ? 1
+}:
 
 rustPlatform.buildRustPackage rec {
   name = "dpi-lib";
diff --git a/templates/chisel/nix/gcd/gcd.nix b/templates/chisel/nix/gcd/gcd.nix
index 0198a8c..42dd4bb 100644
--- a/templates/chisel/nix/gcd/gcd.nix
+++ b/templates/chisel/nix/gcd/gcd.nix
@@ -1,14 +1,23 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: 2024 Jiuyang Liu <liu@jiuyang.me>
 
-{ lib, stdenv, fetchMillDeps, makeWrapper, jdk21
-
-# chisel deps
-, mill, espresso, circt-full, jextract-21, add-determinism
+{ lib
+, stdenv
+, fetchMillDeps
+, makeWrapper
+, jdk21
+
+  # chisel deps
+, mill
+, espresso
+, circt-full
+, jextract-21
+, add-determinism
 
 , projectDependencies
 
-, target }:
+, target
+}:
 
 let
   self = stdenv.mkDerivation rec {
@@ -70,6 +79,8 @@ let
 
     outputs = [ "out" "elaborator" ];
 
+    meta.mainProgram = "elaborator";
+
     buildPhase = ''
       mill -i '__.assembly'
     '';
@@ -86,4 +97,5 @@ let
         --add-flags "--enable-preview -Djava.library.path=${circt-full}/lib -cp $out/share/java/elaborator.jar ${mainClass}"
     '';
   };
-in self
+in
+self
diff --git a/templates/chisel/nix/gcd/rtl.nix b/templates/chisel/nix/gcd/rtl.nix
index 3ac8630..8cd8a77 100644
--- a/templates/chisel/nix/gcd/rtl.nix
+++ b/templates/chisel/nix/gcd/rtl.nix
@@ -1,17 +1,24 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: 2024 Jiuyang Liu <liu@jiuyang.me>
 
-{ lib, stdenvNoCC, circt, mlirbc, mfcArgs ? [
-  "-O=release"
-  "--split-verilog"
-  "--preserve-values=all"
-  "--lowering-options=verifLabels,omitVersionComment"
-  "--strip-debug-info"
-], enable-layers ? [ ] }:
+{ lib
+, stdenvNoCC
+, circt
+, mlirbc
+, mfcArgs ? [
+    "-O=release"
+    "--split-verilog"
+    "--preserve-values=all"
+    "--lowering-options=verifLabels,omitVersionComment"
+    "--strip-debug-info"
+  ]
+, enable-layers ? [ ]
+}:
 let
   processLayer = lib.map (str: "./" + lib.replaceStrings [ "." ] [ "/" ] str);
   enableLayersDirs = processLayer enable-layers;
-in stdenvNoCC.mkDerivation {
+in
+stdenvNoCC.mkDerivation {
   name = "${mlirbc.name}-rtl";
   nativeBuildInputs = [ circt ];
 
diff --git a/templates/chisel/nix/gcd/vcs-wrapper.sh b/templates/chisel/nix/gcd/vcs-wrapper.sh
new file mode 100755
index 0000000..52efad2
--- /dev/null
+++ b/templates/chisel/nix/gcd/vcs-wrapper.sh
@@ -0,0 +1,42 @@
+#!@shell@
+
+_EXTRA_ARGS="$@"
+
+if ((${VERBOSE:-0})); then
+  set -x
+fi
+
+_DATE_BIN=@dateBin@
+_VCS_SIM_BIN=@vcsSimBin@
+_VCS_SIM_DAIDIR=@vcsSimDaidir@
+_VCS_FHS_ENV=@vcsFhsEnv@
+
+_NOW=$("$_DATE_BIN" "+%Y-%m-%d-%H-%M-%S")
+_GCD_SIM_RESULT_DIR=${GCD_SIM_RESULT_DIR:-"gcd-sim-result"}
+_CURRENT="$_GCD_SIM_RESULT_DIR"/all/"$_NOW"
+mkdir -p "$_CURRENT"
+ln -sfn "all/$_NOW" "$_GCD_SIM_RESULT_DIR/result"
+
+cp "$_VCS_SIM_BIN" "$_CURRENT/"
+cp -r "$_VCS_SIM_DAIDIR" "$_CURRENT/"
+
+chmod -R +w "$_CURRENT"
+
+pushd "$_CURRENT" >/dev/null
+
+_emu_name=$(basename "$_VCS_SIM_BIN")
+_daidir=$(basename "$_VCS_SIM_DAIDIR")
+
+export LD_LIBRARY_PATH="$PWD/$_daidir:$LD_LIBRARY_PATH"
+
+"$_VCS_FHS_ENV" -c "./$_emu_name $_EXTRA_ARGS" &> >(tee vcs-emu-journal.log)
+
+if ((${DATA_ONLY:-0})); then
+  rm -f "./$_emu_name"
+fi
+
+set -e _emu_name _daidir
+
+popd >/dev/null
+
+echo "VCS emulator finished, result saved in $_GCD_SIM_RESULT_DIR/result"
diff --git a/templates/chisel/nix/gcd/vcs.nix b/templates/chisel/nix/gcd/vcs.nix
index 68ec6f0..40bb5c2 100644
--- a/templates/chisel/nix/gcd/vcs.nix
+++ b/templates/chisel/nix/gcd/vcs.nix
@@ -1,9 +1,19 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: 2024 Jiuyang Liu <liu@jiuyang.me>
 
-{ lib, bash, stdenv, rtl, dpi-lib, vcs-fhs-env }:
-let binName = "gcd-vcs-simulator";
-in stdenv.mkDerivation {
+{ lib
+, bash
+, stdenv
+, rtl
+, dpi-lib
+, vcs-fhs-env
+, runCommand
+}:
+
+let
+  binName = "gcd-vcs-simulator";
+in
+stdenv.mkDerivation (finalAttr: {
   name = "vcs";
 
   # Add "sandbox = relaxed" into /etc/nix/nix.conf, and run `systemctl restart nix-daemon`
@@ -15,6 +25,8 @@ in stdenv.mkDerivation {
 
   src = rtl;
 
+  meta.mainProgram = binName;
+
   buildPhase = ''
     runHook preBuild
 
@@ -44,6 +56,15 @@ in stdenv.mkDerivation {
     inherit vcs-fhs-env;
     inherit dpi-lib;
     inherit rtl;
+
+    tests.simple-sim = runCommand "${binName}-test" { __noChroot = true; } ''
+      export GCD_SIM_RESULT_DIR="$(mktemp -d)"
+      export DATA_ONLY=1
+      ${finalAttr.finalPackage}/bin/${binName}
+
+      mkdir -p "$out"
+      cp -vr "$GCD_SIM_RESULT_DIR"/result/* "$out/"
+    '';
   };
 
   shellHook = ''
@@ -58,15 +79,14 @@ in stdenv.mkDerivation {
     cp ${binName} $out/lib
     cp -r ${binName}.daidir $out/lib
 
-    # We need to carefully handle string escape here, so don't use makeWrapper
-    tee $out/bin/${binName} <<EOF
-    #!${bash}/bin/bash
-    export LD_LIBRARY_PATH="$out/lib/${binName}.daidir:\$LD_LIBRARY_PATH"
-    _argv="\$@"
-    ${vcs-fhs-env}/bin/vcs-fhs-env -c "$out/lib/${binName} \$_argv"
-    EOF
+    substitute ${./vcs-wrapper.sh} $out/bin/${binName} \
+      --subst-var-by shell "${bash}/bin/bash" \
+      --subst-var-by dateBin "$(command -v date)" \
+      --subst-var-by vcsSimBin "$out/lib/${binName}" \
+      --subst-var-by vcsSimDaidir "$out/lib/${binName}.daidir" \
+      --subst-var-by vcsFhsEnv "${vcs-fhs-env}/bin/vcs-fhs-env"
     chmod +x $out/bin/${binName}
 
     runHook postInstall
   '';
-}
+})
diff --git a/templates/chisel/nix/gcd/verilated.nix b/templates/chisel/nix/gcd/verilated.nix
index b12f1a0..89c6048 100644
--- a/templates/chisel/nix/gcd/verilated.nix
+++ b/templates/chisel/nix/gcd/verilated.nix
@@ -19,6 +19,8 @@ in stdenv.mkDerivation {
     inherit (rtl) target;
   };
 
+  meta.mainProgram = vName;
+
   buildPhase = ''
     runHook preBuild
 
diff --git a/templates/chisel/nix/overlay.nix b/templates/chisel/nix/overlay.nix
index 284863c..55a1ee4 100644
--- a/templates/chisel/nix/overlay.nix
+++ b/templates/chisel/nix/overlay.nix
@@ -3,9 +3,10 @@
 
 final: prev: {
   espresso = final.callPackage ./pkgs/espresso.nix { };
-  mill = let jre = final.jdk21;
-  in (prev.mill.override { inherit jre; }).overrideAttrs
-  (_: { passthru = { inherit jre; }; });
+  mill =
+    let jre = final.jdk21;
+    in (prev.mill.override { inherit jre; }).overrideAttrs
+      (_: { passthru = { inherit jre; }; });
   fetchMillDeps = final.callPackage ./pkgs/mill-builder.nix { };
   circt-full = final.callPackage ./pkgs/circt-full.nix { };
   add-determinism =