diff --git a/.github/workflows/codecov.yml b/.github/workflows/codecov.yml
index adef0f2..6bd23c2 100644
--- a/.github/workflows/codecov.yml
+++ b/.github/workflows/codecov.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index b71063d..edd5a48 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -30,7 +30,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.4
       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/docfx.yml b/.github/workflows/docfx.yml
index 2553e2a..76a97dc 100644
--- a/.github/workflows/docfx.yml
+++ b/.github/workflows/docfx.yml
@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
diff --git a/.github/workflows/dotnetcore.yml b/.github/workflows/dotnetcore.yml
index 577b7af..cc0a59c 100644
--- a/.github/workflows/dotnetcore.yml
+++ b/.github/workflows/dotnetcore.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
diff --git a/.github/workflows/publish-nuget.yml b/.github/workflows/publish-nuget.yml
index ff39d18..7ca7b23 100644
--- a/.github/workflows/publish-nuget.yml
+++ b/.github/workflows/publish-nuget.yml
@@ -8,7 +8,7 @@ jobs:
     name: build, pack & publish
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v2.3.4
 
       # - name: Setup dotnet
       #   uses: actions/setup-dotnet@v1