diff --git a/lerobot/common/datasets/lerobot_dataset.py b/lerobot/common/datasets/lerobot_dataset.py
index 6ef955dd..d8da85d6 100644
--- a/lerobot/common/datasets/lerobot_dataset.py
+++ b/lerobot/common/datasets/lerobot_dataset.py
@@ -1053,7 +1053,7 @@ class MultiLeRobotDataset(torch.utils.data.Dataset):
         super().__init__()
         self.repo_ids = repo_ids
         self.root = Path(root) if root else HF_LEROBOT_HOME
-        self.tolerances_s = tolerances_s if tolerances_s else {repo_id: 1e-4 for repo_id in repo_ids}
+        self.tolerances_s = tolerances_s if tolerances_s else dict.fromkeys(repo_ids, 0.0001)
         # Construct the underlying datasets passing everything but `transform` and `delta_timestamps` which
         # are handled by this class.
         self._datasets = [
diff --git a/lerobot/common/datasets/utils.py b/lerobot/common/datasets/utils.py
index 7e297b35..9d8a54db 100644
--- a/lerobot/common/datasets/utils.py
+++ b/lerobot/common/datasets/utils.py
@@ -240,7 +240,7 @@ def load_episodes_stats(local_dir: Path) -> dict:
 def backward_compatible_episodes_stats(
     stats: dict[str, dict[str, np.ndarray]], episodes: list[int]
 ) -> dict[str, dict[str, np.ndarray]]:
-    return {ep_idx: stats for ep_idx in episodes}
+    return dict.fromkeys(episodes, stats)
 
 
 def load_image_as_numpy(
diff --git a/lerobot/common/datasets/v2/convert_dataset_v1_to_v2.py b/lerobot/common/datasets/v2/convert_dataset_v1_to_v2.py
index acf0282f..024576d7 100644
--- a/lerobot/common/datasets/v2/convert_dataset_v1_to_v2.py
+++ b/lerobot/common/datasets/v2/convert_dataset_v1_to_v2.py
@@ -481,7 +481,7 @@ def convert_dataset(
 
     # Tasks
     if single_task:
-        tasks_by_episodes = {ep_idx: single_task for ep_idx in episode_indices}
+        tasks_by_episodes = dict.fromkeys(episode_indices, single_task)
         dataset, tasks = add_task_index_by_episodes(dataset, tasks_by_episodes)
         tasks_by_episodes = {ep_idx: [task] for ep_idx, task in tasks_by_episodes.items()}
     elif tasks_path:
diff --git a/lerobot/common/utils/logging_utils.py b/lerobot/common/utils/logging_utils.py
index b99c348f..56c9abb2 100644
--- a/lerobot/common/utils/logging_utils.py
+++ b/lerobot/common/utils/logging_utils.py
@@ -94,7 +94,7 @@ class MetricsTracker:
         metrics: dict[str, AverageMeter],
         initial_step: int = 0,
     ):
-        self.__dict__.update({k: None for k in self.__keys__})
+        self.__dict__.update(dict.fromkeys(self.__keys__))
         self._batch_size = batch_size
         self._num_frames = num_frames
         self._avg_samples_per_ep = num_frames / num_episodes