diff --git a/core/lib/Drupal/Component/Utility/SafeMarkup.php b/core/lib/Drupal/Component/Utility/SafeMarkup.php
index ec293d0..c78c144 100644
--- a/core/lib/Drupal/Component/Utility/SafeMarkup.php
+++ b/core/lib/Drupal/Component/Utility/SafeMarkup.php
@@ -251,8 +251,8 @@ public static function checkPlain($text) {
    *   formatting depends on the first character of the key:
    *   - @variable: Escaped to HTML using self::escape(). Use this as the
    *     default choice for anything displayed on a page on the site.
-   *   - %variable: Escaped to HTML and formatted using self::placeholder(),
-   *     which makes the following HTML code:
+   *   - %variable: Escaped to HTML wrapped in <em> tags, which makes the
+   *     following HTML code:
    *     @code
    *       <em class="placeholder">text output here.</em>
    *     @endcode