diff --git a/binder/environment.yml b/binder/environment.yml
index 4b264e7d3..c5b6fdd36 100644
--- a/binder/environment.yml
+++ b/binder/environment.yml
@@ -12,4 +12,5 @@ dependencies:
 - matplotlib
 - numpy
 - nodejs
+- tornado>=6.1
 - xeus-python