diff --git a/core/includes/module.inc b/core/includes/module.inc
index 0ea8e7e..5a17873 100644
--- a/core/includes/module.inc
+++ b/core/includes/module.inc
@@ -1216,14 +1216,20 @@ function module_set_weight($module, $weight) {
  *   An array of module configuration data sorted by weight and name.
  */
 function module_config_sort($data) {
+  // PHP array sorting functions such as uasort() do not work with both keys and
+  // values at the same time, so we achieve weight and name sorting by computing
+  // strings with both information concatenated (weight first, name second) and
+  // use that as a regular string sort reference list via array_multisort(),
+  // compound of "[sign-as-integer][padded-integer-weight][name]"; e.g., given
+  // two modules and weights (spaces added for clarity):
+  // - Block with weight -5: 0 0000000000000000005 block
+  // - Node  with weight  0: 1 0000000000000000000 node
   $sort = array();
   foreach ($data as $name => $weight) {
-    // We can't use the sign directly because + (ASCII 43) is before
-    // - (ASCII 45). So negative nubmers get a 0, non-negative numbers
-    // a 1 prefix.
+    // Prefix negative weights with 0, positive weights with 1.
+    // +/- signs cannot be used, since + (ASCII 43) is before - (ASCII 45).
     $prefix = (int) ($weight >= 0);
-    // PHP_INT_MAX is at most 19 characters so make every number equally
-    // 19 digits long.
+    // The maximum weight is PHP_INT_MAX, so pad all weights to 19 digits.
     $sort[] = $prefix . sprintf('%019d', abs($weight)) . $name;
   }
   array_multisort($sort, SORT_STRING, $data);