diff --git a/docs/requirements.txt b/docs/requirements.txt
index b9cf1a7..71d05ba 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -18,5 +18,6 @@ sphinxcontrib-qthelp
 sphinxcontrib-serializinghtml
 sphinx-reredirects
 sympy
+numpydoc
 chardet