diff --git a/.github/workflows/cron.yml b/.github/workflows/cron.yml
index ca956a3..cef0a7f 100644
--- a/.github/workflows/cron.yml
+++ b/.github/workflows/cron.yml
@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-20.04
     if: github.repository_owner == 'hwdsl2'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@ec3a7ce113134d7a93b817d10a8272cb61118579 # 2.4.0
         with:
           persist-credentials: false
       - name: Check
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 1dc3ecf..4b7cb5c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-20.04
     if: github.repository_owner == 'hwdsl2'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@ec3a7ce113134d7a93b817d10a8272cb61118579 # 2.4.0
         with:
           persist-credentials: false
       - name: Check
@@ -47,7 +47,7 @@ jobs:
     runs-on: ubuntu-20.04
     if: github.repository_owner == 'hwdsl2'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@ec3a7ce113134d7a93b817d10a8272cb61118579 # 2.4.0
         with:
           persist-credentials: false
       - name: Check