diff --git a/rest_framework_bulk/drf3/serializers.py b/rest_framework_bulk/drf3/serializers.py
index 31fff46..ad4b170 100644
--- a/rest_framework_bulk/drf3/serializers.py
+++ b/rest_framework_bulk/drf3/serializers.py
@@ -37,9 +37,10 @@ class BulkListSerializer(ListSerializer):
 
     def update(self, queryset, all_validated_data):
         id_attr = getattr(self.child.Meta, 'update_lookup_field', 'id')
-
+        to_db_value = self.child.Meta.model._meta.get_field(id_attr).to_python
+        
         all_validated_data_by_id = {
-            i.pop(id_attr): i
+            to_db_value(i.pop(id_attr)): i
             for i in all_validated_data
         }