diff --git a/rest_framework_bulk/drf3/serializers.py b/rest_framework_bulk/drf3/serializers.py
index 31fff46..c0ec06e 100644
--- a/rest_framework_bulk/drf3/serializers.py
+++ b/rest_framework_bulk/drf3/serializers.py
@@ -26,6 +26,7 @@ def to_internal_value(self, data):
                 request_method in ('PUT', 'PATCH'))):
             id_field = self.fields[id_attr]
             id_value = id_field.get_value(data)
+            id_value = id_field.to_internal_value(id_value)
 
             ret[id_attr] = id_value