diff --git a/.github/workflows/build-machines-and-homes.yml b/.github/workflows/build-machines-and-homes.yml
index b85e53f..d54e390 100644
--- a/.github/workflows/build-machines-and-homes.yml
+++ b/.github/workflows/build-machines-and-homes.yml
@@ -39,25 +39,6 @@ jobs:
       - name: setup binary cache key
         run: echo -n "${{ secrets.NIX_CACHE_SECRET_KEY }}" | xxd -p -r > ${{ runner.temp }}/cache-priv-key.pem
 
-      - name: Sync repository
-        uses: actions/checkout@v4
-        with:
-          persist-credentials: false
-
-      - name: post-build-hook
-        run: |
-          sudo mkdir -p /etc/nix
-          sudo cp ci/upload-to-cache.sh /etc/nix/
-          sudo chmod +x /etc/nix/upload-to-cache.sh
-
-      - name: setup s3 credentials
-        run: |
-          sudo mkdir /root/.aws
-          echo "[default]" |sudo tee /root/.aws/config |sudo tee /root/.aws/credentials
-          echo "aws_access_key_id=$AWS_ACCESS_KEY_ID" |sudo tee -a /root/.aws/credentials
-          echo "aws_secret_access_key=$AWS_SECRET_ACCESS_KEY" |sudo tee -a /root/.aws/credentials
-          echo "endpoint_url=$AWS_ENDPOINT_URL" |sudo tee -a /root/.aws/config
-
       - name: Install Nix
         uses: cachix/install-nix-action@v30
         with:
@@ -70,13 +51,26 @@ jobs:
             secret-key-files = ${{ runner.temp }}/cache-priv-key.pem
             extra-substituters = https://nixcache.cy7.sh
             extra-trusted-public-keys = nixcache.cy7.sh:DN3d1dt0wnXfTH03oVmTee4KgmdNdB0NY3SuzA8Fwx8=
-            post-build-hook = /etc/nix/upload-to-cache.sh
             download-buffer-size = 1073741824
 
+      - name: Sync repository
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+
       - name: build
         run: |
           nix run nixpkgs#nixos-rebuild build -- -L --flake ".#${{ matrix.machine }}"
 
+      - name: cache
+        run: |
+          nix run \
+            github:cything/nixcp/test-in-ci -- push \
+            --bucket nixcache \
+            --endpoint $AWS_ENDPOINT_URL \
+            --signing-key ${{ runner.temp }}/cache-priv-key.pem \
+            result
+
   build-homes:
     strategy:
       fail-fast: false
@@ -86,7 +80,6 @@ jobs:
           - yt@chunk
         os:
           - ubuntu-latest
-          # - macos-latest
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -105,25 +98,6 @@ jobs:
       - name: setup binary cache key
         run: echo -n "${{ secrets.NIX_CACHE_SECRET_KEY }}" | xxd -p -r > ${{ runner.temp }}/cache-priv-key.pem
 
-      - name: Sync repository
-        uses: actions/checkout@v4
-        with:
-          persist-credentials: false
-
-      - name: post-build-hook
-        run: |
-          sudo mkdir -p /etc/nix
-          sudo cp ci/upload-to-cache.sh /etc/nix/
-          sudo chmod +x /etc/nix/upload-to-cache.sh
-
-      - name: setup s3 credentials
-        run: |
-          sudo mkdir /root/.aws
-          echo "[default]" |sudo tee /root/.aws/config |sudo tee /root/.aws/credentials
-          echo "aws_access_key_id=$AWS_ACCESS_KEY_ID" |sudo tee -a /root/.aws/credentials
-          echo "aws_secret_access_key=$AWS_SECRET_ACCESS_KEY" |sudo tee -a /root/.aws/credentials
-          echo "endpoint_url=$AWS_ENDPOINT_URL" |sudo tee -a /root/.aws/config
-
       - name: Install Nix
         uses: cachix/install-nix-action@v30
         with:
@@ -136,10 +110,23 @@ jobs:
             secret-key-files = ${{ runner.temp }}/cache-priv-key.pem
             extra-substituters = https://nixcache.cy7.sh
             extra-trusted-public-keys = nixcache.cy7.sh:DN3d1dt0wnXfTH03oVmTee4KgmdNdB0NY3SuzA8Fwx8=
-            post-build-hook = /etc/nix/upload-to-cache.sh
             download-buffer-size = 1073741824
 
+      - name: Sync repository
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+
       - name: build
         run: |
           package=".#homeConfigurations."${{ matrix.home }}".activationPackage"
           nix build -L "$package"
+
+      - name: cache
+        run: |
+          nix run \
+            github:cything/nixcp/test-in-ci -- push \
+            --bucket nixcache \
+            --endpoint $AWS_ENDPOINT_URL \
+            --signing-key ${{ runner.temp }}/cache-priv-key.pem \
+            result
diff --git a/.github/workflows/build-packages.yml b/.github/workflows/build-packages.yml
index 343a54f..61527a1 100644
--- a/.github/workflows/build-packages.yml
+++ b/.github/workflows/build-packages.yml
@@ -32,25 +32,6 @@ jobs:
       - name: setup binary cache key
         run: echo -n "${{ secrets.NIX_CACHE_SECRET_KEY }}" | xxd -p -r > ${{ runner.temp }}/cache-priv-key.pem
 
-      - name: Sync repository
-        uses: actions/checkout@v4
-        with:
-          persist-credentials: false
-
-      - name: post-build-hook
-        run: |
-          sudo mkdir -p /etc/nix
-          sudo cp ci/upload-to-cache.sh /etc/nix/
-          sudo chmod +x /etc/nix/upload-to-cache.sh
-
-      - name: setup s3 credentials
-        run: |
-          sudo mkdir /root/.aws
-          echo "[default]" |sudo tee /root/.aws/config |sudo tee /root/.aws/credentials
-          echo "aws_access_key_id=$AWS_ACCESS_KEY_ID" |sudo tee -a /root/.aws/credentials
-          echo "aws_secret_access_key=$AWS_SECRET_ACCESS_KEY" |sudo tee -a /root/.aws/credentials
-          echo "endpoint_url=$AWS_ENDPOINT_URL" |sudo tee -a /root/.aws/config
-
       - name: Install Nix
         uses: cachix/install-nix-action@v30
         with:
@@ -63,10 +44,18 @@ jobs:
             secret-key-files = ${{ runner.temp }}/cache-priv-key.pem
             extra-substituters = https://nixcache.cy7.sh
             extra-trusted-public-keys = nixcache.cy7.sh:DN3d1dt0wnXfTH03oVmTee4KgmdNdB0NY3SuzA8Fwx8=
-            post-build-hook = /etc/nix/upload-to-cache.sh
 
       - run: nix build -L ${{ matrix.package }}
 
+      - name: cache
+        run: |
+          nix run \
+            github:cything/nixcp/test-in-ci -- push \
+            --bucket nixcache \
+            --endpoint $AWS_ENDPOINT_URL \
+            --signing-key ${{ runner.temp }}/cache-priv-key.pem \
+            result
+
       - name: prepare tarball to upload
         run: nix run github:nixos/nixpkgs#gnutar hcvf result.tar result