diff --git a/gym/core.py b/gym/core.py
index e06398e7f..984ea7e0f 100644
--- a/gym/core.py
+++ b/gym/core.py
@@ -107,8 +107,9 @@ class Env(Generic[ObsType, ActType], metaclass=decorator):
     """
 
     # Set this in SOME subclasses
-    metadata = {"render_modes": []}
-    render_mode = None  # define render_mode if your environment supports rendering
+    metadata: Dict[str, Any] = {"render_modes": []}
+    # define render_mode if your environment supports rendering
+    render_mode: Optional[str] = None
     reward_range = (-float("inf"), float("inf"))
     spec: "EnvSpec" = None