diff --git a/.github/workflows/python-tests.yml b/.github/workflows/python-tests.yml
index 79d984d8..b5228ca4 100644
--- a/.github/workflows/python-tests.yml
+++ b/.github/workflows/python-tests.yml
@@ -19,7 +19,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --progress-bar off --upgrade pip setuptools
-          pip install --progress-bar off optuna>=3.0.0
+          pip install --progress-bar off "optuna>=3.0.0"
           pip install --progress-bar off .
           pip install --progress-bar off flake8 black isort mypy
       - run: flake8 . --show-source
@@ -41,7 +41,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --progress-bar off --upgrade pip setuptools
-          pip install --progress-bar off optuna>=3.0.0
+          pip install --progress-bar off "optuna>=3.0.0"
           pip install --progress-bar off .
       - run: python -m unittest
   test-with-optuna-master: