diff --git a/System/Process/CrontabProcess.php b/System/Process/CrontabProcess.php
index 2fd62b4a..b8342d36 100644
--- a/System/Process/CrontabProcess.php
+++ b/System/Process/CrontabProcess.php
@@ -43,7 +43,7 @@ class CrontabProcess extends Process
             $redis = Snowflake::app()->getRedis();
 
             $range = $redis->zRangeByScore(ACrontab::CRONTAB_KEY, '0', (string)$startTime);
-            $redis->zRemRangeByScore(ACrontab::CRONTAB_KEY, 0, $startTime);
+            $redis->zRemRangeByScore(ACrontab::CRONTAB_KEY, '0', (string)$startTime);
             foreach ($range as $value) {
                 $crontab = $redis->get('crontab:' . md5($value));
                 if (empty($crontab) || !($crontab = unserialize($crontab))) {