diff --git a/benchmarl/environments/pettingzoo/multiwalker.py b/benchmarl/environments/pettingzoo/multiwalker.py
index 9ed0f7a7..d51e32dc 100644
--- a/benchmarl/environments/pettingzoo/multiwalker.py
+++ b/benchmarl/environments/pettingzoo/multiwalker.py
@@ -20,4 +20,4 @@ class TaskConfig:
     terminate_reward: float = MISSING
     terminate_on_fall: bool = MISSING
     remove_on_fall: bool = MISSING
-    terrain_length: float = MISSING
+    terrain_length: int = MISSING