diff --git a/core/lib/Drupal/Core/Render/Element.php b/core/lib/Drupal/Core/Render/Element.php
index 53886b6..ac9f066 100644
--- a/core/lib/Drupal/Core/Render/Element.php
+++ b/core/lib/Drupal/Core/Render/Element.php
@@ -85,15 +85,15 @@ public static function children(array &$elements, $sort = FALSE) {
       if ($key === '' || $key[0] !== '#') {
         if (is_array($value)) {
           if (isset($value['#weight'])) {
-            $child_weights[$key] = $value['#weight'];
+            $weight = $value['#weight'];
             $sortable = TRUE;
           }
           else {
-            $child_weights[$key] = 0;
+            $weight = 0;
           }
-          // Add a small number between 0 and 1 to keep the order of insertion
-          // of equal weight elements.
-          $child_weights[$key] += $i / $count;
+          // Supports weight with up to three digit precision and conserve
+          // the insertion order.
+          $child_weights[$key] = floor($weight * 1000) + $i / $count;
         }
         // Only trigger an error if the value is not null.
         // @see http://drupal.org/node/1283892