diff --git a/.github/workflows/on_pull_request.yaml b/.github/workflows/on_pull_request.yaml
index e9f3a3de..38bb974c 100644
--- a/.github/workflows/on_pull_request.yaml
+++ b/.github/workflows/on_pull_request.yaml
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4
 
       - name: Install dependencies
         run: python3 -m pip install tox
diff --git a/.github/workflows/publish.yaml b/.github/workflows/publish.yaml
index 1987d17d..a207064f 100644
--- a/.github/workflows/publish.yaml
+++ b/.github/workflows/publish.yaml
@@ -32,7 +32,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4
         with:
           fetch-depth: 0
           ref: ${{ inputs.source_branch }}
diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 5575fcb5..8bd5de32 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -25,7 +25,7 @@ jobs:
       - unit-test
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4
 
       - name: Setup operator environment
         uses: charmed-kubernetes/actions-operator@main