diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 4869dac..fdd9ee4 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -26,7 +26,7 @@ jobs:
     container: dockfool/cake-docker:latest
     steps:
       - name: Checkout source
-        uses: actions/checkout@v3.5.3
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
         with:
           fetch-depth: 0
           submodules: recursive
@@ -45,7 +45,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout source
-        uses: actions/checkout@v3.5.3
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
         with:
           fetch-depth: 0
           submodules: recursive
@@ -70,7 +70,7 @@ jobs:
     runs-on: macos-latest
     steps:
       - name: Checkout source
-        uses: actions/checkout@v3.5.3
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
         with:
           fetch-depth: 0
           submodules: recursive
@@ -95,7 +95,7 @@ jobs:
     runs-on: windows-latest
     steps:
       - name: Checkout source
-        uses: actions/checkout@v3.5.3
+        uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4.0.0
         with:
           fetch-depth: 0
           submodules: recursive