diff --git a/function/heroku.php b/function/heroku.php
index 6c4e2dc..ba91f84 100644
--- a/function/heroku.php
+++ b/function/heroku.php
@@ -93,6 +93,7 @@ function setConfig($arr, $disktag = '')
         if ($disktag_s!='') $tmp['disktag'] = substr($disktag_s, 0, -1);
         else $tmp['disktag'] = '';
     }
+    foreach ($tmp as $key => $val) if ($val=='') $tmp[$key]=null;
 //    echo '正式设置：'.json_encode($tmp,JSON_PRETTY_PRINT).'
 //';
     return setHerokuConfig($tmp, getConfig('function_name'), getConfig('APIKey'));