diff --git a/setup.py b/setup.py
index cae33f578..666cb8a75 100644
--- a/setup.py
+++ b/setup.py
@@ -11,7 +11,7 @@ extras = {
   'board_game' : ['pachi-py>=0.0.19'],
   'box2d': ['Box2D-kengz'],
   'classic_control': ['PyOpenGL'],
-  'mujoco': ['mujoco_py>=0.4.3', 'imageio'],
+  'mujoco': ['mujoco_py<1.0.0,>=0.4.3', 'imageio'],
   'parameter_tuning': ['keras', 'theano'],
 }