diff --git a/lib/qiniu/auth.rb b/lib/qiniu/auth.rb
index e28679b..80d818d 100755
--- a/lib/qiniu/auth.rb
+++ b/lib/qiniu/auth.rb
@@ -51,6 +51,7 @@ def initialize(bucket,
           :scope                  => "scope"               ,
           :is_prefixal_scope      => "isPrefixalScope"     ,
           :save_key               => "saveKey"             ,
+          :force_save_key         => "forceSaveKey"        ,
           :end_user               => "endUser"             ,
           :return_url             => "returnUrl"           ,
           :return_body            => "returnBody"          ,