diff --git a/docs/requirements-docs.txt b/docs/requirements-docs.txt
index 605befe..3f9b956 100644
--- a/docs/requirements-docs.txt
+++ b/docs/requirements-docs.txt
@@ -1,2 +1,4 @@
 -r ../requirements-dev.txt
+nbsphinx
+numpydoc>=0.9.0
 git+https://github.com/pandas-dev/pydata-sphinx-theme.git@master