diff --git a/src/Valitron/Validator.php b/src/Valitron/Validator.php
index 4404d48..313d7e8 100644
--- a/src/Valitron/Validator.php
+++ b/src/Valitron/Validator.php
@@ -1079,7 +1079,7 @@ class Validator
      * instance only.
      *
      * @param string                     $name
-     * @param mixed                         $callback
+     * @param callable                         $callback
      * @param string                     $message
      * @throws \InvalidArgumentException
      */
@@ -1095,7 +1095,7 @@ class Validator
      * Register new validation rule callback
      *
      * @param  string                    $name
-     * @param  mixed                     $callback
+     * @param  callable                     $callback
      * @param  string                    $message
      * @throws \InvalidArgumentException
      */