diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index fa1509a0..9e71bc7c 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -8,7 +8,7 @@ jobs:
         python-version: [3.8, 3.11]
     steps:
       - name: Check out repository code
-        uses: actions/checkout@v4
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v5
@@ -37,7 +37,7 @@ jobs:
         node-version: [16]
     steps:
       - name: Check out repository code
-        uses: actions/checkout@v4
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Set up Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v4
diff --git a/.github/workflows/integration-test.yaml b/.github/workflows/integration-test.yaml
index 46f4aaf0..667c3a8a 100644
--- a/.github/workflows/integration-test.yaml
+++ b/.github/workflows/integration-test.yaml
@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           path: mitx-grading-library