diff --git a/examples/seq2seq/utils.py b/examples/seq2seq/utils.py
index 6ab72e7ce64e..a96535e46417 100644
--- a/examples/seq2seq/utils.py
+++ b/examples/seq2seq/utils.py
@@ -269,7 +269,7 @@ def __init__(self, tokenizer, data_args, tpu_num_cores=None):
         ), f"pad_token_id is not defined for ({self.tokenizer.__class__.__name__}), it must be defined."
         self.data_args = data_args
         self.tpu_num_cores = tpu_num_cores
-        self.dataset_kwargs = {"add_prefix_space": isinstance(tokenizer, BartTokenizer)}
+        self.dataset_kwargs = {"add_prefix_space": True} if isinstance(tokenizer, BartTokenizer) else {}
         if data_args.src_lang is not None:
             self.dataset_kwargs["src_lang"] = data_args.src_lang
         if data_args.tgt_lang is not None: