diff --git a/.github/workflows/pr-hygiene.yaml b/.github/workflows/pr-hygiene.yaml
new file mode 100644
index 0000000..d747a26
--- /dev/null
+++ b/.github/workflows/pr-hygiene.yaml
@@ -0,0 +1,54 @@
+name: PR hygiene checks
+on:
+  pull_request:
+    types: [assigned, opened, synchronize, reopened]
+    branches:
+      - main
+  merge_group:
+    types: [checks_requested]
+
+jobs:
+  check-pr-size:
+    name: Check PR size
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Download script
+        run: |
+          curl -sSLO \
+            "https://raw.githubusercontent.com/dannywillems/toolbox/main/pr-hygiene/check-pr-size.sh"
+          chmod +x check-pr-size.sh
+      - name: Check PR size
+        run: >
+          ./check-pr-size.sh
+          "${{ github.event.pull_request.base.sha }}"
+
+  check-commit-messages:
+    name: Check commit messages
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Download scripts
+        run: |
+          for script in check-title-length.sh \
+            check-no-fixup.sh check-commit-body.sh; do
+            curl -sSLO \
+              "https://raw.githubusercontent.com/dannywillems/toolbox/main/pr-hygiene/${script}"
+            chmod +x "${script}"
+          done
+      - name: Check title length
+        run: >
+          ./check-title-length.sh
+          "${{ github.event.pull_request.base.sha }}"
+      - name: Check no fixup/WIP commits
+        run: >
+          ./check-no-fixup.sh
+          "${{ github.event.pull_request.base.sha }}"
+      - name: Check commit body on large changes
+        run: >
+          ./check-commit-body.sh
+          "${{ github.event.pull_request.base.sha }}"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2c7c563..ea174ae 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,10 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Infrastructure
+
+- CI: add PR hygiene checks using dannywillems/toolbox ([a4c3b19], [#69])
+
 ## [2.0.1] - 2026-03-17
 
 ### Changed
@@ -204,6 +208,7 @@ and this project adheres to
 
 <!-- Commit links -->
 
+[a4c3b19]: https://github.com/LeakIX/l9format-python/commit/a4c3b19
 [953d604]: https://github.com/LeakIX/l9format-python/commit/953d604
 [72bf877]: https://github.com/LeakIX/l9format-python/commit/72bf877
 [c9216ba]: https://github.com/LeakIX/l9format-python/commit/c9216ba
@@ -307,4 +312,5 @@ and this project adheres to
 [#64]: https://github.com/LeakIX/l9format-python/pull/64
 [#65]: https://github.com/LeakIX/l9format-python/pull/65
 [#67]: https://github.com/LeakIX/l9format-python/pull/67
+[#69]: https://github.com/LeakIX/l9format-python/pull/69
 [#43]: https://github.com/LeakIX/l9format-python/issues/43