diff --git a/app/models/formsemestre.py b/app/models/formsemestre.py
index 599fcda20..2234fdfa1 100644
--- a/app/models/formsemestre.py
+++ b/app/models/formsemestre.py
@@ -170,10 +170,10 @@ class FormSemestre(db.Model):
         else:
             modimpls.sort(
                 key=lambda m: (
-                    m.module.ue.numero,
-                    m.module.matiere.numero,
-                    m.module.numero,
-                    m.module.code,
+                    m.module.ue.numero or 0,
+                    m.module.matiere.numero or 0,
+                    m.module.numero or 0,
+                    m.module.code or "",
                 )
             )
         return modimpls