diff --git a/snuvote/app/vote/dto/requests.py b/snuvote/app/vote/dto/requests.py
index 09965ab..d6d9082 100644
--- a/snuvote/app/vote/dto/requests.py
+++ b/snuvote/app/vote/dto/requests.py
@@ -71,4 +71,4 @@ class CreateVoteRequest(BaseModel):
 
 class ParticipateVoteRequest(BaseModel):
     participated_choice_ids: List[int]
-    participation_code: str | None
\ No newline at end of file
+    participation_code: str | None = None
\ No newline at end of file