diff --git a/ptuning/main.py b/ptuning/main.py
index d1c4977..1776055 100644
--- a/ptuning/main.py
+++ b/ptuning/main.py
@@ -147,7 +147,7 @@ def main():
                 targets.append(examples[response_column][i])
 
         inputs = [prefix + inp for inp in inputs]
-        model_inputs = tokenizer(inputs, max_length=data_args.max_source_length, truncation=True)
+        model_inputs = tokenizer(inputs, max_length=data_args.max_source_length, truncation=True, padding=True)
         labels = tokenizer(text_target=targets, max_length=max_target_length, truncation=True)
 
         if data_args.ignore_pad_token_for_loss: