diff --git a/custom_components/ecole_directe/ecole_directe_helper.py b/custom_components/ecole_directe/ecole_directe_helper.py
index 1f464f0..68a5931 100644
--- a/custom_components/ecole_directe/ecole_directe_helper.py
+++ b/custom_components/ecole_directe/ecole_directe_helper.py
@@ -534,10 +534,10 @@ def get_grade(data):
         "out_of": data.get("noteSur").replace(".", ","),
         "default_out_of": data.get("noteSur").replace(".", ","),
         "grade_out_of": data.get("valeur") + "/" + data.get("noteSur"),
-        "coefficient": data.get("coef").replace(".", ","),
-        "class_average": data.get("moyenneClasse").replace(".", ","),
-        "max": str(data.get("maxClasse")).replace(".", ","),
-        "min": str(data.get("minClasse")).replace(".", ","),
+        "coefficient": (data.get("coef") or "").replace(".", ","),
+        "class_average": (data.get("moyenneClasse") or "").replace(".", ","),
+        "max": str(data.get("maxClasse") or "").replace(".", ","),
+        "min": str(data.get("minClasse") or "").replace(".", ","),
         "is_bonus": "",
         "is_optionnal": "",
         "is_out_of_20": "",