diff --git a/dreamer4/dreamer4.py b/dreamer4/dreamer4.py
index 31df3d8..7d333d2 100644
--- a/dreamer4/dreamer4.py
+++ b/dreamer4/dreamer4.py
@@ -82,6 +82,7 @@ class Experience:
     log_probs: tuple[Tensor, Tensor] | None = None
     values: Tensor | None = None
     step_size: int | None = None
+    lens: Tensor | None = None,
     agent_index: int = 0
     is_from_world_model: bool = True
 
@@ -2560,12 +2561,16 @@ class DynamicsWorldModel(Module):
 
         # returning agent actions, rewards, and log probs + values for policy optimization
 
+        batch, device = latents.shape[0], latents.device
+        experience_lens = torch.full((batch,), time_steps, device = device)
+
         gen = Experience(
             latents = latents,
             video = video,
             proprio = proprio if has_proprio else None,
             step_size = step_size,
             agent_index = agent_index,
+            lens = experience_lens,
             is_from_world_model = True
         )
 
diff --git a/pyproject.toml b/pyproject.toml
index c126938..ab2e923 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "dreamer4"
-version = "0.0.72"
+version = "0.0.73"
 description = "Dreamer 4"
 authors = [
     { name = "Phil Wang", email = "lucidrains@gmail.com" }