diff --git a/src/tasknet/tasks.py b/src/tasknet/tasks.py
index 2b7e6cc..d54edea 100755
--- a/src/tasknet/tasks.py
+++ b/src/tasknet/tasks.py
@@ -13,7 +13,7 @@
 from frozendict import frozendict as fdict
 import funcy as fc
 import evaluate
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 import re
 from transformers.tokenization_utils_base import PreTrainedTokenizerBase
 import inspect
@@ -199,7 +199,7 @@ def __call__(self, features):
 class MultipleChoice(Classification):
     task_type = "MultipleChoice"
     num_labels:int = 2
-    data_collator:...= DataCollatorForMultipleChoice()
+    data_collator:...= field(default_factory=DataCollatorForMultipleChoice)
     choices: ... = tuple()
     s1: str = "inputs"
         
@@ -345,7 +345,7 @@ def check(self):
 @dataclass
 class Seq2SeqLM(Task):
     task_type='Seq2SeqLM'
-    data_collator:...=DataCollatorForSeq2Seq(None)
+    data_collator:... = field(default_factory=lambda: DataCollatorForSeq2Seq(None))
     s1:str=''
     s2:str=''
     metric:...=evaluate.load("bleu")