diff --git a/core/ScheduledTime/Monthly.php b/core/ScheduledTime/Monthly.php
index <HASH>..<HASH> 100644
--- a/core/ScheduledTime/Monthly.php
+++ b/core/ScheduledTime/Monthly.php
@@ -33,7 +33,7 @@ class Piwik_ScheduledTime_Monthly extends Piwik_ScheduledTime
 									date('Y', $currentTime)
 									);
 
-		$nextMonthLength = cal_days_in_month(CAL_GREGORIAN, date('n', $rescheduledTime), date('Y', $rescheduledTime));
+		$nextMonthLength = date('t', $rescheduledTimeU);
 
 		// Sets scheduled day
 		if ( $this->day !== null )
Refs #<I>
Using date() as it is built-in (VS cal_days_in_month which requires library)
Unit tests pass so I think it is similar?

git-svn-id: <URL>