diff --git a/requirements_rtd.txt b/requirements_rtd.txt
index be803cda..301ba275 100644
--- a/requirements_rtd.txt
+++ b/requirements_rtd.txt
@@ -17,3 +17,4 @@ sphinx_gallery
 vaex-core
 vaex-hdf5
 nbformat==4.4.0
+jupyter_client<7.0