diff --git a/requirements.txt b/requirements.txt
index 45f053d..078ce6c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,4 +5,4 @@ scikit-learn>=0.18
 scipy>=0.18.0
 seaborn>=0.7.1
 autograd>=1.1.7
-gym
+gym>=0.6.0,<=0.22.0