diff --git a/src/www/interfaces.php b/src/www/interfaces.php
index ca71e3d137..89e55536aa 100644
--- a/src/www/interfaces.php
+++ b/src/www/interfaces.php
@@ -2492,7 +2492,26 @@ include("head.inc");
                           <td>
                             <select name="dhcp6-ia-pd-len" class="selectpicker" data-style="btn-default" id="dhcp6-ia-pd-len">
 <?php
-                            foreach(array("none" => "None", 16 => "48", 12 => "52", 8 => "56", 4 => "60", 2 => "62", 1 => "63", 0 => "64") as $bits => $length):?>
+                            foreach(array(
+                              'none' => 'None',
+                              16 => '48',
+                              15 => '49',
+                              14 => '50',
+                              13 => '51',
+                              12 => '52',
+                              11 => '53',
+                              10 => '54',
+                              9 => '55',
+                              8 => '56',
+                              7 => '57',
+                              6 => '58',
+                              5 => '59',
+                              4 => '60',
+                              3 => '61',
+                              2 => '62',
+                              1 => '63',
+                              0 => '64',
+                            ) as $bits => $length): ?>
                               <option value="<?=$bits;?>" <?=$bits == $pconfig['dhcp6-ia-pd-len'] ? "selected=\"selected\"" : "";?>>
                                   <?=$length;?>
                               </option>