diff --git a/requirements.txt b/requirements.txt
index ac9d9f1..84b0840 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,5 @@
 sphinx>=2.4.4
+ipykernel>=4.5.1
 ipywidgets>=7.0.0
 IPython
 nbconvert>=5.4