diff --git a/app/scodoc/sco_cost_formation.py b/app/scodoc/sco_cost_formation.py
index 16429881..334d3a0a 100644
--- a/app/scodoc/sco_cost_formation.py
+++ b/app/scodoc/sco_cost_formation.py
@@ -34,8 +34,6 @@ from flask import request
 
 from app.models import FormSemestre
 from app.scodoc.gen_tables import GenTable
-from app.scodoc import sco_formsemestre
-from app.scodoc import sco_moduleimpl
 from app.scodoc import sco_preferences
 import app.scodoc.sco_utils as scu
 import sco_version
@@ -65,16 +63,18 @@ def formsemestre_table_estim_cost(
             {
                 "code": modimpl.module.code or "",
                 "titre": modimpl.module.titre,
-                "heures_cours": modimpl.module.heures_cours,
-                "heures_td": modimpl.module.heures_td * n_group_td,
-                "heures_tp": modimpl.module.heures_tp * n_group_tp,
+                "heures_cours": modimpl.module.heures_cours or 0.0,
+                "heures_td": (modimpl.module.heures_td or 0.0) * n_group_td,
+                "heures_tp": (modimpl.module.heures_tp or 0.0) * n_group_tp,
             }
         )
 
     # calcul des heures:
-    for t in rows:
-        t["HeqTD"] = (
-            t["heures_td"] + coef_cours * t["heures_cours"] + coef_tp * t["heures_tp"]
+    for row in rows:
+        row["HeqTD"] = (
+            row["heures_td"]
+            + coef_cours * row["heures_cours"]
+            + coef_tp * row["heures_tp"]
         )
     sum_cours = sum([t["heures_cours"] for t in rows])
     sum_td = sum([t["heures_td"] for t in rows])