diff --git a/app/but/validations_view.py b/app/but/validations_view.py
index 94c02c10..713d4e13 100644
--- a/app/but/validations_view.py
+++ b/app/but/validations_view.py
@@ -95,9 +95,10 @@ def get_ue_validation_by_niveau(
                     validation.ue.id} pas de niveau de competence"""
             )
             continue
+        semestre_idx = validation.ue.guess_semestre_idx()
         key = (
             validation.ue.niveau_competence.id,
-            "impair" if validation.ue.semestre_idx % 2 else "pair",
+            "impair" if semestre_idx % 2 else "pair",
         )
         existing = ue_validation_by_niveau.get(key, None)
         if (not existing) or (
diff --git a/app/tables/bilan_ues.py b/app/tables/bilan_ues.py
index ac73c8d6..ee10aa7a 100644
--- a/app/tables/bilan_ues.py
+++ b/app/tables/bilan_ues.py
@@ -168,6 +168,7 @@ class RowEtudWithUEs(RowEtudWithInfos):
             return
         best_validation = _best_validation(validations)
         moy_ue = best_validation.moy_ue
+        ue_semestre_idx = best_validation.ue.guess_semestre_idx()
         note_class = ""
         if moy_ue is None:
             moy_ue = scu.NO_NOTE_STR
@@ -181,10 +182,10 @@ class RowEtudWithUEs(RowEtudWithInfos):
             raw_content=moy_ue,
             classes=[note_class],
             column_classes={"note_ue"},
-            group=f"col_s{best_validation.ue.semestre_idx}",
+            group=f"col_s{ue_semestre_idx}",
         )
         if self.table.is_apc:
-            class_cursus = f"cursus_BUT{(best_validation.ue.semestre_idx+1)//2}"
+            class_cursus = f"cursus_BUT{(ue_semestre_idx+1)//2}"
         else:
             class_cursus = ""
         self.add_cell(
@@ -192,5 +193,5 @@ class RowEtudWithUEs(RowEtudWithInfos):
             self.table.ue_titles[key],
             best_validation.code,
             column_classes={"code_ue", class_cursus},
-            group=f"col_s{best_validation.ue.semestre_idx}",
+            group=f"col_s{ue_semestre_idx}",
         )