diff --git a/.github/workflows/publish-packages.yml b/.github/workflows/publish-packages.yml
index 720033bfe..df146e77b 100644
--- a/.github/workflows/publish-packages.yml
+++ b/.github/workflows/publish-packages.yml
@@ -17,11 +17,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Check out repo
-      uses: actions/checkout@v4
+      uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
     - name: Set up Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@f677139bbe7f9c59b41e40162b753c062f5d49a3 # v5.2.0
       with:
-        python-version: "3.11"
+        python-version: "3.12"
     - name: Install dependencies
       run: |
         # We must explicitly install the requirements so that we can force
@@ -44,7 +44,7 @@ jobs:
       run:
         python -m pytest -v tests/
     - name: Upload artifact
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@50769540e7f4bd5e21e526ee35c689e35e0d6874 # v4.4.0
       with:
           name: release
           path: dist/
@@ -54,18 +54,18 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Download artifact
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
             name: release
             path: dist/
       - name: Publish package to TestPyPI
         if: ${{ inputs.upload_to_test }}
-        uses: pypa/gh-action-pypi-publish@release/v1
+        uses: pypa/gh-action-pypi-publish@0ab0b79471669eb3a4d647e625009c62f9f3b241 # v1.10.1
         with:
           repository_url: https://test.pypi.org/legacy/
           password: ${{ secrets.TEST_PYPI_API_TOKEN }}
       - name: Publish package to PyPI
         if: ${{ !inputs.upload_to_test }}
-        uses: pypa/gh-action-pypi-publish@release/v1
+        uses: pypa/gh-action-pypi-publish@0ab0b79471669eb3a4d647e625009c62f9f3b241 # v1.10.1
         with:
           password: ${{ secrets.PYPI_API_TOKEN }}
diff --git a/.github/workflows/run-pytest.yml b/.github/workflows/run-pytest.yml
index 6f7247c1d..72a72f1e4 100644
--- a/.github/workflows/run-pytest.yml
+++ b/.github/workflows/run-pytest.yml
@@ -59,9 +59,9 @@ jobs:
             python: '3.12'
             dependencies: 'minimal'
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
     - name: Set up Python ${{ matrix.python }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@f677139bbe7f9c59b41e40162b753c062f5d49a3 # v5.2.0
       with:
         python-version: ${{ matrix.python }}
     - name: Install newest dependencies
@@ -87,6 +87,6 @@ jobs:
     - name: Test with pytest
       run: |
         pytest --cov=signac --cov-config=pyproject.toml --cov-report=xml tests/ -v
-    - uses: codecov/codecov-action@v4
+    - uses: codecov/codecov-action@e28ff129e5465c2c0dcc6f003fc735cb6ae0c673 # v4.5.0
       with:
         token: ${{ secrets.CODECOV_TOKEN }}