diff --git a/.github/workflows/documentation.yaml b/.github/workflows/documentation.yaml
index dc38585..518b6e2 100644
--- a/.github/workflows/documentation.yaml
+++ b/.github/workflows/documentation.yaml
@@ -22,6 +22,7 @@ jobs:
                       -e "${BME_PROJECT_DIR}/src"
       - name: Sphinx build
         run: |
+          source ./env/bin/activate
           cd "${GITHUB_WORKSPACE}/src" && make doc
       - name: Deploy to GitHub Pages
         uses: peaceiris/actions-gh-pages@v3