diff --git a/docs/requirements_1.txt b/docs/requirements_1.txt
index 3e7b901..fff82a2 100644
--- a/docs/requirements_1.txt
+++ b/docs/requirements_1.txt
@@ -9,3 +9,4 @@ six
 nbsphinx
 nbsphinx_link
 jupyter-sphinx
+ipykernel