diff --git a/.forgejo/workflows/check-since.sh b/.forgejo/workflows/check-since.sh
new file mode 100755
index 0000000..123eb59
--- /dev/null
+++ b/.forgejo/workflows/check-since.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+git rev-list "$1"..HEAD | while read -r ref; do
+    git switch "$ref"
+    nix flake check --accept-flake-config
+done
diff --git a/.forgejo/workflows/ci.yaml b/.forgejo/workflows/ci.yaml
index d36c6e0..0872da2 100644
--- a/.forgejo/workflows/ci.yaml
+++ b/.forgejo/workflows/ci.yaml
@@ -11,14 +11,40 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: https://github.com/docker/setup-qemu-action@v3
-      - uses: actions/checkout@v4
-      - uses: https://github.com/cachix/install-nix-action@v26
+      - name: Checkout
+        run: |
+          set -x
+          git init /workspace/kitchen/rice
+          cd /workspace/kitchen/rice
+          git remote add origin ${{ env.GITHUB_SERVER_URL }}/${{ env.GITHUB_REPOSITORY }}
+          if [[ ${{ github.event_name }} == pull_request ]]; then
+            ref="refs/remotes/pull/${{ github.event.pull_request.number }}/head"
+          else
+            ref="refs/remotes/${{ github.event.base_ref }}"
+          fi
+          git fetch origin :"$ref"
+          git switch --detach "$ref"
+      - name: Setup qemu
+        uses: https://github.com/docker/setup-qemu-action@v3
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
+      - name: Install nix
+        uses: https://github.com/cachix/install-nix-action@v26
         with:
           nix_path: nixpkgs=channel:nixos-unstable
           github_access_token: '${{ secrets.GH_TOKEN }}'
-      - uses: https://github.com/cachix/cachix-action@v14
+      - name: Setup cachix
+        uses: https://github.com/cachix/cachix-action@v14
         with:
           name: kitchen
           authToken: '${{ secrets.CACHIX_TOKEN }}'
-      - run: nix flake check --accept-flake-config
+      - name: Run tests
+        run: |
+          set -x
+          if [[ ${{ github.event_name }} == push ]]; then
+            ref="HEAD~$(echo "${{ toJSON(github.event.commits) }}" | nix run nixpkgs#jq length)"
+          else
+            ref="${{ github.event.base_ref }}"
+          fi
+          "$PWD"/.forgejo/workflows/check-since.sh "$ref"