diff --git a/requirements-docs.txt b/requirements-docs.txt
index 25c8c2c..128ae8b 100644
--- a/requirements-docs.txt
+++ b/requirements-docs.txt
@@ -3,4 +3,4 @@
 
 # documentation generation support
 Sphinx==2.2.1
-numpydoc==0.5
+numpydoc==0.9.1