diff --git a/app/auth/models.py b/app/auth/models.py
index d71ecf3f..117dd7c5 100644
--- a/app/auth/models.py
+++ b/app/auth/models.py
@@ -329,7 +329,7 @@ class Role(db.Model):
     """Roles for ScoDoc"""
 
     id = db.Column(db.Integer, primary_key=True)
-    name = db.Column(db.String(64), unique=True)
+    name = db.Column(db.String(64), unique=True)  # TODO: , nullable=False))
     default = db.Column(db.Boolean, default=False, index=True)
     permissions = db.Column(db.BigInteger)  # 64 bits
     users = db.relationship("User", secondary="user_role", viewonly=True)
@@ -388,7 +388,7 @@ class UserRole(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     user_id = db.Column(db.Integer, db.ForeignKey("user.id"))
     role_id = db.Column(db.Integer, db.ForeignKey("role.id"))
-    dept = db.Column(db.String(64))  # dept acronym
+    dept = db.Column(db.String(64))  # dept acronym ou NULL
     user = db.relationship(
         User, backref=db.backref("user_roles", cascade="all, delete-orphan")
     )
diff --git a/app/views/users.py b/app/views/users.py
index 3e3e7e8d..e3326e6b 100644
--- a/app/views/users.py
+++ b/app/views/users.py
@@ -171,15 +171,17 @@ def create_user_form(user_name=None, edit=0, all_roles=1):
         }
         if not initvalues["active"]:
             editable_roles_set = set()  # can't change roles of a disabled user
-    editable_roles_strings = {r.name + "_" + dept for (r, dept) in editable_roles_set}
-    orig_roles_strings = {r.name + "_" + dept for (r, dept) in orig_roles}
+    editable_roles_strings = {
+        r.name + "_" + (dept or "") for (r, dept) in editable_roles_set
+    }
+    orig_roles_strings = {r.name + "_" + (dept or "") for (r, dept) in orig_roles}
     # add existing user roles
     displayed_roles = list(editable_roles_set.union(orig_roles))
     displayed_roles.sort(key=lambda x: (x[1], x[0].name))
-    displayed_roles_strings = [r.name + "_" + dept for (r, dept) in displayed_roles]
-    displayed_roles_labels = [
-        "{dept}: {r.name}".format(dept=dept, r=r) for (r, dept) in displayed_roles
+    displayed_roles_strings = [
+        r.name + "_" + (dept or "") for (r, dept) in displayed_roles
     ]
+    displayed_roles_labels = [f"{dept}: {r.name}" for (r, dept) in displayed_roles]
     disabled_roles = {}  # pour desactiver les roles que l'on ne peut pas editer
     for i in range(len(displayed_roles_strings)):
         if displayed_roles_strings[i] not in editable_roles_strings: