diff --git a/.github/workflows/1_create_release_pr.yml b/.github/workflows/1_create_release_pr.yml
index 5e6229b..0bbe58f 100644
--- a/.github/workflows/1_create_release_pr.yml
+++ b/.github/workflows/1_create_release_pr.yml
@@ -35,7 +35,7 @@ jobs:
       uses: cylc/release-actions/stage-1/sanitize-inputs@v1
 
     - name: Checkout repo
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
       with:
         ref: ${{ env.BASE_REF }}
         fetch-depth: 0  # need to fetch all commits to check contributors
diff --git a/.github/workflows/2_auto_publish_release.yml b/.github/workflows/2_auto_publish_release.yml
index 9ce87e7..1c02d1d 100644
--- a/.github/workflows/2_auto_publish_release.yml
+++ b/.github/workflows/2_auto_publish_release.yml
@@ -21,7 +21,7 @@ jobs:
     steps:
 
     - name: Checkout repo
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
       with:
         ref: ${{ env.MERGE_SHA }}
 
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 1120923..b0d1b23 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -31,7 +31,7 @@ jobs:
     name: ${{ matrix.os }} py-${{ matrix.python }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup Python
         uses: mamba-org/setup-micromamba@v2
diff --git a/.github/workflows/shortlog.yml b/.github/workflows/shortlog.yml
index 8e3d666..206dcbc 100644
--- a/.github/workflows/shortlog.yml
+++ b/.github/workflows/shortlog.yml
@@ -15,7 +15,7 @@ jobs:
     timeout-minutes: 10
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0  # need to fetch all commits to check contributors
 
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 60d7528..28972a8 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -32,7 +32,7 @@ jobs:
       PYTEST_ADDOPTS: --cov --cov-append --color=yes
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Configure Python
         uses: mamba-org/setup-micromamba@v2
@@ -57,7 +57,7 @@ jobs:
           pip install -e .[tests]
 
       - name: Checkout FCM
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: ${{ github.event.inputs.fcm_repo || 'metomi/fcm' }}
           ref: ${{ github.event.inputs.fcm_ref || 'master' }}
@@ -117,7 +117,7 @@ jobs:
     timeout-minutes: 2
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Configure Python
         uses: mamba-org/setup-micromamba@v2
@@ -155,7 +155,7 @@ jobs:
     timeout-minutes: 2
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Download coverage artifacts
         uses: actions/download-artifact@v6
diff --git a/.github/workflows/update_copyright.yml b/.github/workflows/update_copyright.yml
index ed0b989..84864ee 100644
--- a/.github/workflows/update_copyright.yml
+++ b/.github/workflows/update_copyright.yml
@@ -11,7 +11,7 @@ jobs:
     timeout-minutes: 10
     steps:
     - name: Checkout repo
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
 
     - name: Configure git
       uses: cylc/release-actions/configure-git@v1