diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 78063c3..f069c72 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -52,7 +52,7 @@ jobs:
     - name: Install Stetl 📦
       run: |
         pip install --upgrade pip
-        pip install nose2
+        pip install nose2 sphinx_rtd_theme
         python3 setup.py install
     - name: run unit tests ⚙️
       run: |