diff --git a/lerobot/common/policies/act/configuration_act.py b/lerobot/common/policies/act/configuration_act.py
index 7a5819b749..8ad5e27e5c 100644
--- a/lerobot/common/policies/act/configuration_act.py
+++ b/lerobot/common/policies/act/configuration_act.py
@@ -91,6 +91,7 @@ class ACTConfig(PreTrainedConfig):
     """
 
     # Input / output structure.
+    type: str = "act"
     n_obs_steps: int = 1
     chunk_size: int = 100
     n_action_steps: int = 100
diff --git a/lerobot/common/policies/diffusion/configuration_diffusion.py b/lerobot/common/policies/diffusion/configuration_diffusion.py
index e73c65fe9a..577fcbc646 100644
--- a/lerobot/common/policies/diffusion/configuration_diffusion.py
+++ b/lerobot/common/policies/diffusion/configuration_diffusion.py
@@ -104,6 +104,7 @@ class DiffusionConfig(PreTrainedConfig):
     """
 
     # Inputs / output structure.
+    type: str = "diffusion"
     n_obs_steps: int = 2
     horizon: int = 16
     n_action_steps: int = 8