diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index a110245..31b8e9c 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -18,7 +18,7 @@ jobs:
           - "3.3"
           - "3.4"
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: "${{ matrix.ruby-version }}"
diff --git a/.github/workflows/gem-push.yaml b/.github/workflows/gem-push.yaml
index c276be6..463cdf6 100644
--- a/.github/workflows/gem-push.yaml
+++ b/.github/workflows/gem-push.yaml
@@ -12,7 +12,7 @@ jobs:
       contents: read
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@a37ce9120846195fa4ece8f58b268e6043cb2f26 # v3
     - name: Set up Ruby 3.4
       uses: ruby/setup-ruby@v1
       with: