diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index 1a1a0a2..c006fa8 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -10,7 +10,7 @@ jobs:
   CodeQL-Build:
     runs-on: ubuntu-18.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
 
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v1
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 20d2b35..a33f4cb 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -9,7 +9,7 @@ jobs:
   release:
     runs-on: ubuntu-18.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
 
       - name: Dump GitHub context
         env:
diff --git a/.github/workflows/test-action.yml b/.github/workflows/test-action.yml
index 0f4b9c3..f63cb80 100644
--- a/.github/workflows/test-action.yml
+++ b/.github/workflows/test-action.yml
@@ -19,7 +19,7 @@ jobs:
           - 'latest'
           - '0.4.0'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
 
       - name: Setup mdBook
         uses: peaceiris/actions-mdbook@v1.1.14
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 0f3eb2b..1765e81 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -21,7 +21,7 @@ jobs:
           - 'macos-latest'
           - 'windows-latest'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
 
       - name: Read .nvmrc
         run: echo "::set-output name=NVMRC::$(cat .nvmrc)"
diff --git a/.github/workflows/update-major-tag.yml b/.github/workflows/update-major-tag.yml
index c06cab8..91939f2 100644
--- a/.github/workflows/update-major-tag.yml
+++ b/.github/workflows/update-major-tag.yml
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-18.04
     steps:
 
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v2.3.4
 
     - name: Update major tag
       if: github.event.release.prerelease == false