diff --git a/app/auth/models.py b/app/auth/models.py
index 8743850d4..37bbf9868 100644
--- a/app/auth/models.py
+++ b/app/auth/models.py
@@ -296,7 +296,7 @@ class User(UserMixin, db.Model):
                 self.user_name = data["user_name"]
             if "password" in data:
                 self.set_password(data["password"])
-        if not invalid_user_name(self.user_name):
+        if invalid_user_name(self.user_name):
             raise ValueError(f"invalid user_name: {self.user_name}")
         # Roles: roles_string is "Ens_RT, Secr_RT, ..."
         if "roles_string" in data:
diff --git a/app/views/users.py b/app/views/users.py
index e6400882a..31c6bf45d 100644
--- a/app/views/users.py
+++ b/app/views/users.py
@@ -337,8 +337,9 @@ def create_user_form(user_name=None, edit=0, all_roles=True):
                     "title": "Pseudo (login)",
                     "size": 20,
                     "allow_null": False,
-                    "explanation": "nom utilisé pour la connexion. Doit être unique parmi tous les utilisateurs."
-                    "Lettres ou chiffres uniquement.",
+                    "explanation": """nom utilisé pour la connexion.
+                        Doit être unique parmi tous les utilisateurs.
+                        Lettres ou chiffres uniquement.""",
                 },
             ),
             ("formsemestre_id", {"input_type": "hidden"}),