diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index bb25475..02eae2b 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -25,7 +25,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v3
+      uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
       with:
         # We must fetch at least the immediate parents so that if this is
         # a pull request then we can checkout the head.
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 5d462e9..51076c3 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -7,7 +7,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
       - name: Set up JDK
         uses: actions/setup-java@v3
         with:
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index c59831c..9843aaa 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,7 +16,7 @@ jobs:
         java: [ 8, 11, 17, 18 ]
     name: Java ${{ matrix.java }} test.
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4
       - name: Setup java
         uses: actions/setup-java@v3
         with: