diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index fd4e35e..13d6ebe 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -19,7 +19,7 @@ jobs:
         os: [ubuntu-latest,macos-latest,windows-latest]
     steps:
     - name: Retrieve the source code
-      uses: actions/checkout@v2
+      uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
     - id: conda-root
       name: Set CONDA_ROOT
       run: |
@@ -56,7 +56,7 @@ jobs:
         pyver: ["3.8","3.9","3.10","3.11"]
     steps:
     - name: Retrieve the source code
-      uses: actions/checkout@v2
+      uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
       with:
         fetch-depth: 0
     - id: conda-root
@@ -95,7 +95,7 @@ jobs:
     if: github.event_name == 'push'
     steps:
     - name: Retrieve the source code
-      uses: actions/checkout@v2
+      uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
       with:
         fetch-depth: 0
     - name: Download the build artifacts