diff --git a/setup.cfg b/setup.cfg
index 1c13fdc92..b5fa9edb1 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -27,7 +27,7 @@ install_requires =
     bokeh~=2.0
     humanfriendly~=10.0
     ipytree~=0.2
-    traitlets~=5.9
+    traitlets~=5.4
     ipywidgets~=7.7
     widgetsnbextension<3.6.3
     pymysql~=0.9