diff --git a/apps/news/serializers.py b/apps/news/serializers.py
index 2c7983d1..c0df73a4 100644
--- a/apps/news/serializers.py
+++ b/apps/news/serializers.py
@@ -232,9 +232,9 @@ class NewsBackOfficeBaseSerializer(NewsBaseSerializer):
 
     def create(self, validated_data):
         slugs = validated_data.get('slugs')
-        slugs_list = list(map(lambda x: x.lower(), slugs.values()))
-        slugs_set = set(slugs_list)
         if slugs:
+            slugs_list = list(map(lambda x: x.lower(), slugs.values()))
+            slugs_set = set(slugs_list)
             if models.News.objects.filter(
                     slugs__values__contains=list(slugs.values())
             ).exists() or len(slugs_list) != len(slugs_set):
@@ -249,9 +249,9 @@ class NewsBackOfficeBaseSerializer(NewsBaseSerializer):
 
     def update(self, instance, validated_data):
         slugs = validated_data.get('slugs')
-        slugs_list = list(map(lambda x: x.lower(), slugs.values()))
-        slugs_set = set(slugs_list)
         if slugs:
+            slugs_list = list(map(lambda x: x.lower(), slugs.values()))
+            slugs_set = set(slugs_list)
             if models.News.objects.filter(
                     slugs__values__contains=list(slugs.values())
             ).exists() or len(slugs_list) != len(slugs_set):