diff --git a/mpcontribs-sidecars/kernel_gateway/requirements.txt b/mpcontribs-sidecars/kernel_gateway/requirements.txt
index 836a6e8e7..4897b825b 100644
--- a/mpcontribs-sidecars/kernel_gateway/requirements.txt
+++ b/mpcontribs-sidecars/kernel_gateway/requirements.txt
@@ -1,5 +1,6 @@
 blinker==1.4
 ipywidgets==7.6.3
+jupyter-client<7
 jupyter-kernel-gateway==2.5.0
 kaleido==0.2.1
 mpcontribs-client==3.13.0