diff --git a/.github/workflows/json-lint.yml b/.github/workflows/json-lint.yml
index 4ab99b0..7969d49 100644
--- a/.github/workflows/json-lint.yml
+++ b/.github/workflows/json-lint.yml
@@ -23,7 +23,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@v4
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Run JSON Lint
         run: jq . gemini-extension.json
\ No newline at end of file
diff --git a/.github/workflows/markdown-checks.yml b/.github/workflows/markdown-checks.yml
index 331bed1..a7337c8 100644
--- a/.github/workflows/markdown-checks.yml
+++ b/.github/workflows/markdown-checks.yml
@@ -24,7 +24,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@v4
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Link Checker
         uses: lycheeverse/lychee-action@v2.0.2
diff --git a/.github/workflows/package-and-upload-assets.yml b/.github/workflows/package-and-upload-assets.yml
index 5f1f52c..18e9247 100644
--- a/.github/workflows/package-and-upload-assets.yml
+++ b/.github/workflows/package-and-upload-assets.yml
@@ -39,7 +39,7 @@ jobs:
     
     steps:
       - name: Checkout code at the new tag
-        uses: actions/checkout@v4
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
         with:
           ref: ${{ github.event.release.tag_name }}
 
@@ -117,10 +117,10 @@ jobs:
       contents: write
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Download all archives from workflow artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5
         with:
           path: release-archives
 
diff --git a/.github/workflows/presubmit-tests.yml b/.github/workflows/presubmit-tests.yml
index bca3258..787c919 100644
--- a/.github/workflows/presubmit-tests.yml
+++ b/.github/workflows/presubmit-tests.yml
@@ -22,7 +22,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@v4
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Install Gemini CLI
         run: npm install @google/gemini-cli