diff --git a/pixivpy3/models.py b/pixivpy3/models.py
index fa9a950..b2d81a0 100644
--- a/pixivpy3/models.py
+++ b/pixivpy3/models.py
@@ -113,7 +113,7 @@ class UserInfo(BasePixivpyModel):
     account: str
     profile_image_urls: ProfileImageUrls
     comment: Optional[str] = None  # present only on `user_detail` endpoint
-    is_followed: Optional[bool]
+    is_followed: Optional[bool] = None
     is_access_blocking_user: Optional[bool] = None