diff --git a/cron/cron.php b/cron/cron.php
index ce894c3..15b3fb3 100644
--- a/cron/cron.php
+++ b/cron/cron.php
@@ -23,8 +23,7 @@ class cron {
      */
     public static function check($class){
         if( !\class_exists($class) ||
-            !\is_array($parents = \class_parents($class)) ||
-            !\array_search('SYSTEM\CRON\cronjob', $parents)){
+            !((new $class) instanceof \SYSTEM\CRON\cronjob)){
             return false;}
         return true;}
     
diff --git a/cron/cron_cache_delete.php b/cron/cron_cache_delete.php
index ae3a79f..441a647 100644
--- a/cron/cron_cache_delete.php
+++ b/cron/cron_cache_delete.php
@@ -14,7 +14,7 @@ namespace SYSTEM\CRON;
 /**
  * Conjob Class provided by System to delete System Cache.
  */
-class cron_cache_delete extends \SYSTEM\CRON\cronjob{
+class cron_cache_delete implements \SYSTEM\CRON\cronjob{
     /**
      * Run the Cronjob and delete all Cache entries.
      *
diff --git a/cron/cron_log2sqlite.php b/cron/cron_log2sqlite.php
index be16d31..ea7e29a 100644
--- a/cron/cron_log2sqlite.php
+++ b/cron/cron_log2sqlite.php
@@ -14,7 +14,7 @@ namespace SYSTEM\CRON;
 /**
  * Conjob Class provided by System to extract Logentries into sqlite files.
  */
-class cron_log2sqlite extends \SYSTEM\CRON\cronjob{
+class cron_log2sqlite implements \SYSTEM\CRON\cronjob{
     /**
      * Run the Cronjob and extract Data from log, write it to sqlite files
      *
diff --git a/cron/cronjob.php b/cron/cronjob.php
index ddba794..b075f06 100644
--- a/cron/cronjob.php
+++ b/cron/cronjob.php
@@ -14,11 +14,11 @@ namespace SYSTEM\CRON;
 /**
  * Conjob Class provided by System to derive from for custom Cronjobs.
  */
-abstract class cronjob{
+interface cronjob{
     /**
      * Run the Cronjob and execute its task
      *
      * @return int Return a Cronstatus for the Cron Class to update the db.
      */
-    public abstract static function run();
+    public static function run();
 }
\ No newline at end of file
diff --git a/sai/modules/saimod_sys_cron/saimod_sys_cron.php b/sai/modules/saimod_sys_cron/saimod_sys_cron.php
index 2c6f813..4ed5074 100644
--- a/sai/modules/saimod_sys_cron/saimod_sys_cron.php
+++ b/sai/modules/saimod_sys_cron/saimod_sys_cron.php
@@ -9,7 +9,8 @@ class saimod_sys_cron extends \SYSTEM\SAI\SaiModule {
         $i = 0;
         while($r = $res->next()){
             $r['selected_0'] = $r['selected_1'] = $r['selected_2'] = $r['selected_3'] = '';
-            $r['next'] = date('Y-m-d H:i:s',\SYSTEM\CRON\cron::next($r['class']));
+            $r['next'] = \SYSTEM\time::time_ago_string(\SYSTEM\CRON\cron::next($r['class']));
+            $r['last_run'] = \SYSTEM\time::time_ago_string(\strtotime($r['last_run']));
             $r['selected_'.$r['status']] = 'selected';
             $r['i'] = $i++;
             $vars['content'] .= \SYSTEM\PAGE\replace::replaceFile((new \SYSTEM\PSAI('modules/saimod_sys_cron/tpl/list_entry.tpl'))->SERVERPATH(), $r);}