diff --git a/apps/enm/serializers.py b/apps/enm/serializers.py
index 8701a05d..89b908b2 100644
--- a/apps/enm/serializers.py
+++ b/apps/enm/serializers.py
@@ -13,6 +13,7 @@ class MpointSerializer(CustomModelSerializer):
     ep_monitored_name = serializers.CharField(source='ep_monitored.name', read_only=True)
     ep_belong_name = serializers.CharField(source='ep_belong.name', read_only=True)
     material_name = serializers.CharField(source='material.name', read_only=True)
+    formula = serializers.CharField(allow_blank=True)
     class Meta:
         model = Mpoint
         fields = '__all__'