diff --git a/db/upgrade.php b/db/upgrade.php
index 244083d..225e2c5 100644
--- a/db/upgrade.php
+++ b/db/upgrade.php
@@ -45,7 +45,9 @@ defined('MOODLE_INTERNAL') || die();
 /**
  * Copies a string field to int field
  *
- * @param int $oldversion
+ * @param string $table the name of table
+ * @param string $from the name of source field
+ * @param string $to the name of destination field 
  */
 function mpgame_db_copy_string_to_int( $table, $from, $to) {
     global $CFG, $DB;