diff --git a/mani_skill/trajectory/replay_trajectory.py b/mani_skill/trajectory/replay_trajectory.py
index 4750cd810b..84ca072675 100644
--- a/mani_skill/trajectory/replay_trajectory.py
+++ b/mani_skill/trajectory/replay_trajectory.py
@@ -94,6 +94,14 @@ class ReplayResult:
 
 def sanity_check_and_format_seed(episode):
     """sanity checks the trajectory seed aligns with the episode seed. reformats the reset kwargs seed if missing or formatted wrong"""
+    # normalize episode_seed to a scalar int (may be stored as numpy array or list)
+    episode_seed = episode["episode_seed"]
+    if isinstance(episode_seed, np.ndarray):
+        episode_seed = episode_seed.item() if episode_seed.ndim == 0 else episode_seed[0]
+    elif isinstance(episode_seed, (list, tuple)):
+        episode_seed = episode_seed[0]
+    episode["episode_seed"] = int(episode_seed)
+
     if "seed" in episode["reset_kwargs"]:
         if isinstance(episode["reset_kwargs"]["seed"], list):