diff --git a/core/lib/Drupal/Component/Utility/Crypt.php b/core/lib/Drupal/Component/Utility/Crypt.php
index 6ebdc4a..a1b47b5 100644
--- a/core/lib/Drupal/Component/Utility/Crypt.php
+++ b/core/lib/Drupal/Component/Utility/Crypt.php
@@ -160,7 +160,7 @@ public static function hashEquals($known_string, $user_string) {
    *   The number of random bytes to fetch and base64 encode.
    *
    * @return string
-   *   The base64 encoded result will have a length of up to 4 * $count.
+   *   The base64 encoded result will have a length of ceil($count * 4 / 3).
    *
    * @see \Drupal\Component\Utility\Crypt::randomBytes()
    */