diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e275b8d..ee332f9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-22.04
 
     steps:
-    - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608
+    - uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633
 
     # Our tests require Nim to be installed to `/nim` because some error messages contain
     # e.g. `/nim/lib/pure/unittest.nim(654)`.
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-22.04
 
     steps:
-    - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608
+    - uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633
 
     - name: Download all `exercism/nim` exercises
       run: git clone --depth 1 https://github.com/exercism/nim.git
@@ -72,7 +72,7 @@ jobs:
         # Fail if the output JSON is not as expected.
         diff results.json expected_results.json
 
-    - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608
+    - uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633
       with:
         repository: 'ynfle/diff'
         ref: 'ae470e7702fd07a6ea850b2a6f2de701130fa048'
diff --git a/.github/workflows/lint_dockerfile.yml b/.github/workflows/lint_dockerfile.yml
index 507d1d3..8d0093e 100644
--- a/.github/workflows/lint_dockerfile.yml
+++ b/.github/workflows/lint_dockerfile.yml
@@ -7,7 +7,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608
+        uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633
 
       - name: Run hadolint
         uses: hadolint/hadolint-action@54c9adbab1582c2ef04b2016b760714a4bfde3cf
diff --git a/.github/workflows/shellcheck.yml b/.github/workflows/shellcheck.yml
index 0a08119..c8a8f56 100644
--- a/.github/workflows/shellcheck.yml
+++ b/.github/workflows/shellcheck.yml
@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608
+        uses: actions/checkout@9bb56186c3b09b4f86b1c65136769dd318469633
 
       - name: Run shellcheck
         uses: ludeeus/action-shellcheck@00cae500b08a931fb5698e11e79bfbd38e612a38