diff --git a/docs/docs-env.yml b/docs/docs-env.yml
index 75311cfd7..3068f652f 100644
--- a/docs/docs-env.yml
+++ b/docs/docs-env.yml
@@ -19,3 +19,4 @@ dependencies:
     - lxml
     - numpydoc
     - widgetsnbextension
+    - mock