diff --git a/calsocial/models.py b/calsocial/models.py
index 1598a54..a21035b 100644
--- a/calsocial/models.py
+++ b/calsocial/models.py
@@ -265,7 +265,7 @@ class Profile(db.Model):  # pylint: disable=too-few-public-methods
             domain = ''
         else:
             username = self.username
-            domain = '@' + self.domain
+            domain = f'@{self.domain}'
 
         return f'<Profile {self.id}(@{username}{domain})>'