diff --git a/.github/workflows/release_libs.yaml b/.github/workflows/release_libs.yaml
index 608b8ee3..2825beff 100644
--- a/.github/workflows/release_libs.yaml
+++ b/.github/workflows/release_libs.yaml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4
         with:
           fetch-depth: 0
       - name: Release charm library
diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 8bd5de32..34d39696 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4
 
       - name: Install dependencies
         run: python -m pip install tox