diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e360488..799eab7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,7 +11,7 @@ jobs:
   test:
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
         with:
           submodules: recursive
       - name: Run Tests in Docker
diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index 6ba43ed..9678daf 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -13,7 +13,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4 # 2.3.4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # 2.3.4
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@f95db51fddba0c2d1ec667646a06c2ce06100226 # 3.0.0