diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index 22fc7508..b4ca1693 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Build Docker images
         run: "make docker-images"
       - name: Fix permissions
@@ -45,7 +45,7 @@ jobs:
       USE_CLIENT_IMAGE: 'true'
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Build Docker images
         run: "make docker-images"
       - name: Pull server_image
@@ -68,7 +68,7 @@ jobs:
           - 'Dockerfile.test-server'
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run docker build
         run: 'file=${{ matrix.dockerfile }} && docker build -t "learn-ocaml-${file#*.}" -f "$file" .'
 
diff --git a/.github/workflows/build-macos.yml b/.github/workflows/build-macos.yml
index 80814b04..315785ef 100644
--- a/.github/workflows/build-macos.yml
+++ b/.github/workflows/build-macos.yml
@@ -17,6 +17,6 @@ jobs:
     runs-on: macos-14
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Build learn-ocaml
         run: 'sh .ci-macosx.sh'
diff --git a/.github/workflows/check-update-index.yml b/.github/workflows/check-update-index.yml
index e9b7d644..50c20bac 100644
--- a/.github/workflows/check-update-index.yml
+++ b/.github/workflows/check-update-index.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Execute the script
         run: ./scripts/update-index.sh
diff --git a/.github/workflows/deploy-master.yml b/.github/workflows/deploy-master.yml
index 039fe22f..3d17a76d 100644
--- a/.github/workflows/deploy-master.yml
+++ b/.github/workflows/deploy-master.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Set up Docker Buildx
         # cf. https://github.com/docker/buildx/blob/master/docs/reference/buildx_build.md#image
         # and https://docs.docker.com/engine/reference/commandline/buildx_create/#driver
@@ -53,7 +53,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Set up Docker Buildx
         # cf. https://github.com/docker/buildx/blob/master/docs/reference/buildx_build.md#image
         # and https://docs.docker.com/engine/reference/commandline/buildx_create/#driver
@@ -95,7 +95,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Set up Docker Buildx
         # cf. https://github.com/docker/buildx/blob/master/docs/reference/buildx_build.md#image
         # and https://docs.docker.com/engine/reference/commandline/buildx_create/#driver
diff --git a/.github/workflows/opam-publish.yml b/.github/workflows/opam-publish.yml
index a469e890..29392099 100644
--- a/.github/workflows/opam-publish.yml
+++ b/.github/workflows/opam-publish.yml
@@ -32,7 +32,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Prepare target package repository
         id: prep
         run: |
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index f5d93167..f9faee31 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -43,7 +43,7 @@ jobs:
     steps:
       - name: Check out the repo
         # Mandatory step (otherwise, gh could raise "fatal: Not a git repository")
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Download workflow artifacts
         # cf. https://github.com/actions/download-artifact/issues/3
         uses: dawidd6/action-download-artifact@v2
@@ -98,7 +98,7 @@ jobs:
         run: tag="${{ needs.release-please.outputs.tag_name }}"; echo "::set-output name=tag::${tag#v}"
         id: tag
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Set up Docker Buildx
         # cf. https://github.com/docker/buildx/blob/master/docs/reference/buildx_build.md#image
         # and https://docs.docker.com/engine/reference/commandline/buildx_create/#driver
@@ -143,7 +143,7 @@ jobs:
         run: tag="${{ needs.release-please.outputs.tag_name }}"; echo "::set-output name=tag::${tag#v}"
         id: tag
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Set up Docker Buildx
         # cf. https://github.com/docker/buildx/blob/master/docs/reference/buildx_build.md#image
         # and https://docs.docker.com/engine/reference/commandline/buildx_create/#driver
@@ -192,7 +192,7 @@ jobs:
         run: tag="${{ needs.release-please.outputs.tag_name }}"; echo "::set-output name=tag::${tag#v}"
         id: tag
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Set up Docker Buildx
         # cf. https://github.com/docker/buildx/blob/master/docs/reference/buildx_build.md#image
         # and https://docs.docker.com/engine/reference/commandline/buildx_create/#driver
diff --git a/.github/workflows/static-builds.yml b/.github/workflows/static-builds.yml
index 5531bfdb..d580046d 100644
--- a/.github/workflows/static-builds.yml
+++ b/.github/workflows/static-builds.yml
@@ -25,7 +25,7 @@ jobs:
         # we could use an env var, albeit it would be less convenient
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Build learn-ocaml-compilation
         run: 'docker build -t learn-ocaml-compilation --target=compilation .'
       - name: 'Build ${{ matrix.arch_dir }}.zip'
@@ -50,7 +50,7 @@ jobs:
         # we could use an env var, albeit it would be less convenient
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Build the binaries
         run: |
           ./scripts/static-build.sh
@@ -82,7 +82,7 @@ jobs:
         # we could use an env var, albeit it would be less convenient
     steps:
       - name: Check out the repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Show OS version
         run: |
           sw_vers