diff --git a/studio/backend/core/training/trainer.py b/studio/backend/core/training/trainer.py
index c72a54af00..2e37cad189 100644
--- a/studio/backend/core/training/trainer.py
+++ b/studio/backend/core/training/trainer.py
@@ -1871,7 +1871,10 @@ class UnslothTrainer:
                 if subset:
                     load_kwargs["name"] = subset
 
-                if dataset_slice_end is not None and dataset_slice_end >= 0:
+                _slice_start = dataset_slice_start or 0
+                if (dataset_slice_end is not None
+                        and dataset_slice_end >= 0
+                        and dataset_slice_end >= _slice_start):
                     # Manual slice — stream only the rows we need instead of
                     # downloading the entire dataset.
                     rows_to_stream = dataset_slice_end + 1