diff --git a/.github/workflows/gem_push.yml b/.github/workflows/gem_push.yml
index 21c20ffd6..3d4a160ff 100644
--- a/.github/workflows/gem_push.yml
+++ b/.github/workflows/gem_push.yml
@@ -19,7 +19,7 @@ jobs:
       contents: write
       id-token: write
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.3
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ruby
diff --git a/.github/workflows/jekyll-gh-pages.yml b/.github/workflows/jekyll-gh-pages.yml
index c4a431b9d..f61b7525c 100644
--- a/.github/workflows/jekyll-gh-pages.yml
+++ b/.github/workflows/jekyll-gh-pages.yml
@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
       - name: Setup Pages
         uses: actions/configure-pages@v6
       - name: Build with Jekyll
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 386f03e46..14c98ed5e 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v6.0.3
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
diff --git a/.github/workflows/mutant.yml b/.github/workflows/mutant.yml
index 7c0819f1e..64c274e34 100644
--- a/.github/workflows/mutant.yml
+++ b/.github/workflows/mutant.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v6.0.3
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 1e1fe605c..723eb912d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,7 +17,7 @@ jobs:
         ruby-version: ['3.3', '3.4', '4.0']
 
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v6.0.3
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
diff --git a/.github/workflows/typecheck.yml b/.github/workflows/typecheck.yml
index 4caa209ad..215c9ad00 100644
--- a/.github/workflows/typecheck.yml
+++ b/.github/workflows/typecheck.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v6.0.3
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
diff --git a/.github/workflows/yardstick.yml b/.github/workflows/yardstick.yml
index 823619873..fbd3607c2 100644
--- a/.github/workflows/yardstick.yml
+++ b/.github/workflows/yardstick.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v6.0.3
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with: