diff --git a/src/gflownet/data/data_source.py b/src/gflownet/data/data_source.py
index cc868758..782f0750 100644
--- a/src/gflownet/data/data_source.py
+++ b/src/gflownet/data/data_source.py
@@ -221,10 +221,10 @@ def create_batch(self, trajs, batch_info):
         batch.num_online = sum(t.get("is_online", 0) for t in trajs)
         batch.num_offline = len(trajs) - batch.num_online
         batch.extra_info = batch_info
-        if "preferences" in trajs[0]['cond_info'].keys():
-            batch.preferences = torch.stack([t['cond_info']["preferences"] for t in trajs])
-        if "focus_dir" in trajs[0]['cond_info'].keys():
-            batch.focus_dir = torch.stack([t['cond_info']["focus_dir"] for t in trajs])
+        if "preferences" in trajs[0]["cond_info"].keys():
+            batch.preferences = torch.stack([t["cond_info"]["preferences"] for t in trajs])
+        if "focus_dir" in trajs[0]["cond_info"].keys():
+            batch.focus_dir = torch.stack([t["cond_info"]["focus_dir"] for t in trajs])
 
         if self.ctx.has_n() and self.cfg.algo.tb.do_predict_n:
             log_ns = [self.ctx.traj_log_n(i["traj"]) for i in trajs]