diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index bc292b8..e068926 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -124,7 +124,7 @@ jobs:
         run: |
           sudo apt-get install python3-sphinx
           source venv/bin/activate
-          pip install sphinxemoji
+          pip install sphinxemoji sphinx_rtd_theme
           cd docsource
           make html