diff --git a/lib/date/date.class.php b/lib/date/date.class.php
index 561e0c7787..5cdee7a468 100644
--- a/lib/date/date.class.php
+++ b/lib/date/date.class.php
@@ -195,7 +195,7 @@ class date
     public static function getThisMonth()
     {
         $begin = date('Y-m') . '-01 00:00:00';
-        $end   = date('Y-m', strtotime('next month')) . '-00 23:59:59';
+        $end   = date('Y-m-d 23:59:59', strtotime("$begin +1 month -1 day"));
         return array('begin' => $begin, 'end' => $end);
     }
 
@@ -208,7 +208,7 @@ class date
     public static function getLastMonth()
     {
         $begin = date('Y-m', strtotime('last month', strtotime(date('Y-m',time()) . '-01 00:00:01'))) . '-01 00:00:00';
-        $end   = date('Y-m', strtotime('this month')) . '-00 23:59:59';
+        $end   = date('Y-m-d 23:59:59', strtotime(date('Y-m-01') . ' -1 day'));
         return array('begin' => $begin, 'end' => $end);
     }