diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 48d43d059..fa4712d7f 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -5,7 +5,7 @@ jobs:
     runs-on: ${{ matrix.platform }}
     strategy:
       matrix:
-        platform: [ubuntu-latest]
+        platform: [ubuntu-latest, windows-latest]
         python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9-dev]
 
     env:
@@ -19,7 +19,15 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
 
-      - name: Install base dependencies
+      # tox fails on Windows if version > 3.8.3
+      - name: Install base dependencies - Windows
+        if: matrix.platform == 'windows-latest'
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install tox==3.8.3 sphinx
+
+      - name: Install base dependencies - Ubuntu
+        if: matrix.platform != 'windows-latest'
         run: |
           python -m pip install --upgrade pip
           python -m pip install tox sphinx