diff --git a/nitrogen/mm_tokenizers.py b/nitrogen/mm_tokenizers.py
index e1e6504..f393216 100644
--- a/nitrogen/mm_tokenizers.py
+++ b/nitrogen/mm_tokenizers.py
@@ -157,6 +157,8 @@ def _prepare_action(self, data: dict):
         ), f"Action dim {n_action_dims} exceeds max allowed {self.max_action_dim}."
 
         # Pad the channel dimension
+        # [batch, 18, 21] -> [batch, 18, 25] badded by zeros on the right.
+        # Action data is left aligned here [btn[0], btn[1], ..., btn[16], j_left[0], j_left[1], j_right[0], j_right[1], 0, 0, 0, 0]
         actions = np.pad(actions, ((0, 0), (0, self.max_action_dim - n_action_dims)), "constant")
 
         # Create mask: [T, max_action_dim]
@@ -239,6 +241,10 @@ def unpack_actions(self, actions):
             j_right = actions[:, :, 2:4]
             buttons = actions[:, :, 4:]
         else:
+            # Action data is still left aligned here [btn[0], btn[1], ..., btn[16], j_left[0], j_left[1], j_right[0], j_right[1], 0, 0, 0, 0].
+            # And the dimensions are [batch, 18, 25], not [batch, 18, 21].
+            # Need to remove padding before using negative indices for extracting j_left, j_right.
+            actions = actions[:, :, :21]
             # Unpack the actions into j_left, j_right, buttons
             buttons = actions[:, :, :-4]
             j_left = actions[:, :, -4:-2]