diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index 732a942..5d8dc99 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -16,6 +16,6 @@ jobs:
         with:
           version: v0.8.15
       - name: Checkout code.
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Compile.
         run: earthly --ci +compile
diff --git a/.github/workflows/conventional-commits.yml b/.github/workflows/conventional-commits.yml
index 2cac899..0c5017e 100644
--- a/.github/workflows/conventional-commits.yml
+++ b/.github/workflows/conventional-commits.yml
@@ -16,7 +16,7 @@ jobs:
         with:
           version: v0.8.15
       - name: Checkout code.
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
diff --git a/.github/workflows/git-history.yml b/.github/workflows/git-history.yml
index c14e19b..871f4d7 100644
--- a/.github/workflows/git-history.yml
+++ b/.github/workflows/git-history.yml
@@ -16,7 +16,7 @@ jobs:
         with:
           version: v0.8.15
       - name: Checkout code.
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
diff --git a/.github/workflows/github-actions-workflows.yml b/.github/workflows/github-actions-workflows.yml
index 7caf5af..95bc61c 100644
--- a/.github/workflows/github-actions-workflows.yml
+++ b/.github/workflows/github-actions-workflows.yml
@@ -16,7 +16,7 @@ jobs:
         with:
           version: v0.8.15
       - name: Checkout code.
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Check GitHub Actions workflows linting.
         run: earthly +check-github-actions-workflows-linting
   formatting:
@@ -28,6 +28,6 @@ jobs:
         with:
           version: v0.8.15
       - name: Checkout code.
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - name: Check formatting.
         run: earthly +check-yaml-formatting