diff --git a/htdocs/cron/card.php b/htdocs/cron/card.php
index 0a68ca211b9..79306fb1d65 100644
--- a/htdocs/cron/card.php
+++ b/htdocs/cron/card.php
@@ -354,7 +354,7 @@ if (($action=="create") || ($action=="edit"))
 	print $langs->trans('CronEvery')."</td>";
 	print "<td><select name=\"nbfrequency\">";
 	for($i=1; $i<=60; $i++){
-		if(($object->frequency/$object->unitfrequency) == $i){
+		if(!is_null($object->unitfrequency) && ($object->frequency/$object->unitfrequency) == $i){
 			print "<option value='".$i."' selected='selected'>".$i."</option>";
 		}
 		else{
diff --git a/htdocs/langs/en_US/main.lang b/htdocs/langs/en_US/main.lang
index 9b8f06f262e..bc962c41846 100644
--- a/htdocs/langs/en_US/main.lang
+++ b/htdocs/langs/en_US/main.lang
@@ -258,6 +258,7 @@ days=days
 Hours=Hours
 Minutes=Minutes
 Seconds=Seconds
+Weeks=Weeks
 Today=Today
 Yesterday=Yesterday
 Tomorrow=Tomorrow