diff --git a/.github/workflows/python_lint.yml b/.github/workflows/python_lint.yml
index 56ca65232..4e7c4d8b2 100644
--- a/.github/workflows/python_lint.yml
+++ b/.github/workflows/python_lint.yml
@@ -25,11 +25,16 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           python-version: "3.8"
-      - name: Install dependencies
+      - name: Install Poetry
         run: |
           python -m pip install --upgrade poetry
           poetry config virtualenvs.create false
-          poetry install --with test
+      - name: Validate poetry.lock
+        run: |
+          poetry lock --no-update
+          git diff --exit-code
+      - name: Install dependencies
+        run: poetry install --with test
       - name: Check code style for voicevox_core_python_api
         run: |
           black --check .