diff --git a/app/scodoc/sco_formsemestre.py b/app/scodoc/sco_formsemestre.py
index 2edd365564..679ede4e27 100644
--- a/app/scodoc/sco_formsemestre.py
+++ b/app/scodoc/sco_formsemestre.py
@@ -93,7 +93,7 @@ _formsemestreEditor = ndb.EditableTable(
 )
 
 
-def get_formsemestre(formsemestre_id, raise_soft_exc=False):
+def get_formsemestre(formsemestre_id: int):
     "list ONE formsemestre"
     if formsemestre_id is None:
         raise ValueError("get_formsemestre: id manquant")
@@ -105,10 +105,8 @@ def get_formsemestre(formsemestre_id, raise_soft_exc=False):
     sems = do_formsemestre_list(args={"formsemestre_id": formsemestre_id})
     if not sems:
         log(f"get_formsemestre: invalid formsemestre_id ({formsemestre_id})")
-        if raise_soft_exc:
-            raise ScoValueError(f"semestre {formsemestre_id} inconnu !")
-        else:
-            raise ValueError(f"semestre {formsemestre_id} inconnu !")
+        raise ScoValueError(f"semestre {formsemestre_id} inconnu !")
+
     g.stored_get_formsemestre[formsemestre_id] = sems[0]
     return sems[0]
 
diff --git a/app/scodoc/sco_groups.py b/app/scodoc/sco_groups.py
index de16785ce8..a3959006e7 100644
--- a/app/scodoc/sco_groups.py
+++ b/app/scodoc/sco_groups.py
@@ -300,9 +300,7 @@ def get_group_infos(group_id, etat=None):  # was _getlisteetud
 
     cnx = ndb.GetDBConnexion()
     group = get_group(group_id)
-    sem = sco_formsemestre.get_formsemestre(
-        group["formsemestre_id"], raise_soft_exc=True
-    )
+    sem = sco_formsemestre.get_formsemestre(group["formsemestre_id"])
 
     members = get_group_members(group_id, etat=etat)
     # add human readable description of state:
diff --git a/app/scodoc/sco_permissions_check.py b/app/scodoc/sco_permissions_check.py
index 2bd637d7eb..d81e07ce29 100644
--- a/app/scodoc/sco_permissions_check.py
+++ b/app/scodoc/sco_permissions_check.py
@@ -7,7 +7,7 @@ from flask import g
 from flask_login import current_user
 
 from app.auth.models import User
-
+from app.models import FormSemestre
 import app.scodoc.notesdb as ndb
 from app.scodoc.sco_permissions import Permission
 from app.scodoc import html_sco_header
@@ -164,18 +164,14 @@ def check_access_diretud(formsemestre_id, required_permission=Permission.ScoImpl
         return True, ""
 
 
-def can_change_groups(formsemestre_id):
+def can_change_groups(formsemestre_id: int) -> bool:
     "Vrai si l'utilisateur peut changer les groupes dans ce semestre"
-    from app.scodoc import sco_formsemestre
-
-    sem = sco_formsemestre.get_formsemestre(formsemestre_id, raise_soft_exc=True)
-    if not sem["etat"]:
+    formsemestre: FormSemestre = FormSemestre.query.get_or_404()
+    if not formsemestre.etat:
         return False  # semestre verrouillé
     if current_user.has_permission(Permission.ScoEtudChangeGroups):
-        return True  # admin, chef dept
-    if current_user.id in sem["responsables"]:
-        return True
-    return False
+        return True  # typiquement admin, chef dept
+    return formsemestre.est_responsable(current_user)
 
 
 def can_handle_passwd(user: User, allow_admindepts=False) -> bool: