diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a7821c5..1cf9cf4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -36,13 +36,17 @@ jobs:
           # exit-zero treats all errors as warnings. the github editor is 127 chars wide
           flake8 . --count --max-complexity=10 --max-line-length=127 --statistics
   test:
-    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        os: [macos-latest, ubuntu-latest, windows-latest]
+        python-version: ["3.9", "3.8", "3.7", "3.6"]
+    runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python 3
         uses: actions/setup-python@v2
         with:
-          python-version: 3.x
+          python-version: ${{ matrix.python-version }}
       - name: Cache dependencies
         uses: actions/cache@v2
         with:
@@ -55,7 +59,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install pytest
-          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+          pip install -r requirements.txt
       - name: Test with pytest
         run: |
           pytest
diff --git a/setup.py b/setup.py
index e644a0d..78ca1ff 100644
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@
 
 setuptools.setup(
     name="pearson-pdf",
-    version="1.0.4",
+    version="1.0.5",
     author="jyooru",
     license="MIT",
     description="Tool to download Pearson books as PDFs.",
@@ -29,6 +29,6 @@
     keywords="pearson, ebook, pearson-ebook, pdf, pearson-pdf",
     packages=setuptools.find_packages(exclude=["tests"]),
     install_requires=["requests", "pillow"],
-    python_requires=">=3.9",  # TODO: support more versions
+    python_requires=">=3.6",
     entry_points={"console_scripts": ["pearson_pdf=pearson_pdf.__main__:main"]},
 )