diff --git a/setup.py b/setup.py
index 1a7dec11ea..b6433a77a7 100644
--- a/setup.py
+++ b/setup.py
@@ -40,7 +40,10 @@
 
 EXTRAS['mujoco'] = [
     'mujoco-py>=2.0,<=2.0.2.8',
-    f'gym[all]=={GYM_VERSION}',
+    # Currently gym is not compatible with mujoco 2.0 because of poor
+    # performance. So here we just install imageio to meet the dependency
+    # requirement of gym's mujoco extra.
+    'imageio',
 ]
 
 EXTRAS['dm_control'] = [