diff --git a/llms/mlx_lm/tuner/trainer.py b/llms/mlx_lm/tuner/trainer.py
index 7d1821d4..392030cb 100644
--- a/llms/mlx_lm/tuner/trainer.py
+++ b/llms/mlx_lm/tuner/trainer.py
@@ -166,7 +166,7 @@ def iterate_delineated_batches(
             for j in batch_idx[i]:
                 prompt, completion = dataset.get_prompt_and_completion(j)
                 prompt_lengths.append(input_length(prompt, completion, tokenizer))
-                full_sequence = [tokenizer.encode(dataset[j]) for j in batch_idx[i]]
+                full_sequence = tokenizer.encode(dataset[j])
                 if full_sequence[-1] != tokenizer.eos_token_id:
                     full_sequence.append(tokenizer.eos_token_id)
                 batch.append(full_sequence)