diff --git a/.github/workflows/run-unittest.yml b/.github/workflows/run-unittest.yml
index 8f71ee6..f17b839 100644
--- a/.github/workflows/run-unittest.yml
+++ b/.github/workflows/run-unittest.yml
@@ -13,6 +13,8 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install dependencies
-        run: pip install -e .
+        run:
+          pip install -e .
+          pip install pydantic  # dev-dependencies from pyproject.toml
       - name: Run tests
         run: python3 tests/tests.py