diff --git a/backend/api/database/room/crud.py b/backend/api/database/room/crud.py
index 122a61d..39deec6 100644
--- a/backend/api/database/room/crud.py
+++ b/backend/api/database/room/crud.py
@@ -37,6 +37,8 @@ def create_room_db(*, room: RoomCreate, user: User | None = None, username: str
         # member = Member(anonymous=anonymous, room=room_obj,
         #                 is_admin=True, id_code=member_id)
         member = create_anonymous_member(username, room_obj, db)
+        if member is None:
+            raise ValueError('Nom d\'utilisateur invalide (4 - 15 caractères)')
         member.is_admin = True
 
         db.add(member)
@@ -168,7 +170,7 @@ def disconnect_member(member: Member, db: Session):
 
 def validate_username(username: str, room: Room, db: Session = Depends(get_session)):
     username = username.strip()
-    if 4 < len(username) > 15:
+    if not (4 <= len(username) <= 15):
         return None
     members = select(Member.anonymous_id).where(
         Member.room_id == room.id, Member.anonymous_id != None)
diff --git a/backend/api/routes/room/consumer.py b/backend/api/routes/room/consumer.py
index 01e3792..2535474 100644
--- a/backend/api/routes/room/consumer.py
+++ b/backend/api/routes/room/consumer.py
@@ -170,7 +170,7 @@ class RoomConsumer(Consumer):
 
         elif username is not None:
             username = username.strip()
-            if 4 > len(username) > 15:
+            if not (4 <= len(username) <= 15):
                 await self.send_error("Nom invalide (4-15 caractères)")
                 return