diff --git a/.github/workflows/generate_documentation.yml b/.github/workflows/generate_documentation.yml
index e62a819..7c55f80 100644
--- a/.github/workflows/generate_documentation.yml
+++ b/.github/workflows/generate_documentation.yml
@@ -39,6 +39,7 @@ jobs:
         mv variant/include/mapbox include/
     - name: build
       run: |
+        python3 -m pip install numpy
         python3 -m pip install pdoc3==0.8.4
         export TOMOTOPY_LANG=${{ matrix.language }}
         python3 setup.py install