diff --git a/src/Illuminate/Support/Str.php b/src/Illuminate/Support/Str.php
index 24d308da4be8..2c3a7cbcb376 100755
--- a/src/Illuminate/Support/Str.php
+++ b/src/Illuminate/Support/Str.php
@@ -221,12 +221,12 @@ public static function random($length = 16)
     {
         $string = '';
 
-        while (($len = static::length($string)) < $length) {
+        while (($len = strlen($string)) < $length) {
             $size = $length - $len;
 
             $bytes = static::randomBytes($size);
 
-            $string .= static::substr(str_replace(['/', '+', '='], '', base64_encode($bytes)), 0, $size);
+            $string .= substr(str_replace(['/', '+', '='], '', base64_encode($bytes)), 0, $size);
         }
 
         return $string;
@@ -255,7 +255,7 @@ public static function quickRandom($length = 16)
     {
         $pool = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
 
-        return static::substr(str_shuffle(str_repeat($pool, $length)), 0, $length);
+        return substr(str_shuffle(str_repeat($pool, $length)), 0, $length);
     }
 
     /**