diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index b0933382..bd8a4bb5 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           fetch-depth: 0  # ensures a reachable tag
 
@@ -75,7 +75,7 @@ jobs:
           - {os: windows-2022, shell: msys2, bin: tform}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           sparse-checkout: .github/actions
           sparse-checkout-cone-mode: false
@@ -146,7 +146,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           sparse-checkout: .github/actions
           sparse-checkout-cone-mode: false
@@ -188,7 +188,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           sparse-checkout: .github/actions
           sparse-checkout-cone-mode: false
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 93f653ed..dd14d165 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -33,7 +33,7 @@ jobs:
           - {bin: tform,   test: extra,   timeout: 60, nthreads: 2, flint: no}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           fetch-depth: 0  # ensures a reachable tag
 
@@ -66,7 +66,7 @@ jobs:
           - {bin: parform, test: default, timeout: 15}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           fetch-depth: 0  # ensures a reachable tag
 
@@ -147,7 +147,7 @@ jobs:
           - {bin: tvorm, test: extra,   nthreads: 2, group: 10/10}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           fetch-depth: 0  # ensures a reachable tag
 
@@ -190,7 +190,7 @@ jobs:
           - {bin: tvorm, test: extra,   timeout: 60, nthreads: 2, flint: no}
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           fetch-depth: 0  # ensures a reachable tag
 
@@ -262,7 +262,7 @@ jobs:
           apt-get install --no-install-recommends -y ca-certificates git libstdc++6:amd64
 
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v6.0.3
         with:
           fetch-depth: 0  # ensures a reachable tag