diff --git a/users/models.py b/users/models.py
index c7503d75..41eb969a 100644
--- a/users/models.py
+++ b/users/models.py
@@ -111,7 +111,7 @@ class UserManager(BaseUserManager):
             raise ValueError('Users must have an username')
 
         if not linux_user_check(pseudo):
-            raise ValueError('Username shall only contain [a-z0-9_-]')
+            raise ValueError('Username shall only contain [a-z0-9-]')
 
         user = self.model(
             pseudo=pseudo,