diff --git a/atari/create_dataset.py b/atari/create_dataset.py
index 96660077..c10c6fe3 100644
--- a/atari/create_dataset.py
+++ b/atari/create_dataset.py
@@ -83,11 +83,11 @@ def create_dataset(num_buffers, num_steps, game, data_dir_prefix, trajectories_p
     rtg = np.zeros_like(stepwise_returns)
     for i in done_idxs:
         i = int(i)
-        curr_traj_returns = stepwise_returns[start_index:i+1] # includes i
+        curr_traj_returns = stepwise_returns[start_index:i]
         for j in range(i-1, start_index-1, -1): # start from i-1
-            rtg_j = curr_traj_returns[j-start_index:i+1-start_index]
-            rtg[j] = sum(rtg_j) # includes i
-        start_index = i+1
+            rtg_j = curr_traj_returns[j-start_index:i-start_index]
+            rtg[j] = sum(rtg_j)
+        start_index = i
     print('max rtg is %d' % max(rtg))
 
     # -- create timestep dataset