diff --git a/core/apps/products/serializers/product.py b/core/apps/products/serializers/product.py
index 40c199b..1c0f43e 100644
--- a/core/apps/products/serializers/product.py
+++ b/core/apps/products/serializers/product.py
@@ -21,4 +21,4 @@ class ProductListSerializer(serializers.ModelSerializer):
         return {
             'id': obj.unity.id,
             'name': obj.unity.name,
-        }
\ No newline at end of file
+        } if obj.unity else None
\ No newline at end of file