diff --git a/docs/environment.yml b/docs/environment.yml
index cac89e9..59f806f 100644
--- a/docs/environment.yml
+++ b/docs/environment.yml
@@ -5,6 +5,7 @@ channels:
 dependencies:
   - ipykernel==5.4.3
   - ipywidgets==7.6.3
+  - notebook<7.0.0
   - jedi==0.17.2
   - jinja2==3.0.3
   - nbsphinx==0.8.8