diff --git a/.github/workflows/autoprefixer.yml b/.github/workflows/autoprefixer.yml
index 63b3a79..76efe0b 100644
--- a/.github/workflows/autoprefixer.yml
+++ b/.github/workflows/autoprefixer.yml
@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout to latest commit
-        uses: actions/checkout@v2.3.4
+        uses: actions/checkout@v2.3.5
 
       - name: Setup Node
         uses: actions/setup-node@v2.4.1
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index bb8531b..2c0d9df 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -39,7 +39,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.5
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
diff --git a/.github/workflows/md-link-checker.yml b/.github/workflows/md-link-checker.yml
index 778d760..18b6e6a 100644
--- a/.github/workflows/md-link-checker.yml
+++ b/.github/workflows/md-link-checker.yml
@@ -8,6 +8,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     # checkout to latest commit
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v2.3.5
     # run markdown linter
     - uses: gaurav-nelson/github-action-markdown-link-check@1.0.13