diff --git a/store/serializers.py b/store/serializers.py
index 86f21cc..8af4a60 100644
--- a/store/serializers.py
+++ b/store/serializers.py
@@ -73,7 +73,7 @@ class ChecklistSerializer(serializers.ModelSerializer):
     previewimage = serializers.ImageField(source='preview_image_url', read_only=True)
 
     promo = serializers.SlugRelatedField(source='promocode', slug_field='name',
-                                         queryset=Promocode.objects.active(), required=False)
+                                         queryset=Promocode.objects.active(), required=False, allow_null=True)
 
     currency = serializers.SerializerMethodField('get_yuan_rate')
     curencycurency2 = serializers.DecimalField(source='price_yuan', required=False, max_digits=10, decimal_places=2)