diff --git a/doc/utils/requirements.txt b/doc/utils/requirements.txt
index 90f7fdf3f6..6d2a096efe 100644
--- a/doc/utils/requirements.txt
+++ b/doc/utils/requirements.txt
@@ -11,3 +11,4 @@ six
 pyyaml
 linkchecker
 ipython
+numpy