diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 00f9d264b9..34d38dafd6 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -5626,7 +5626,7 @@ function wp_generate_uuid4() {
  *
  * @since 4.7.0
  *
- * @param $group Where the cache contents are grouped.
+ * @param string $group Where the cache contents are grouped.
  *
  * @return string $last_changed UNIX timestamp with microseconds representing when the group was last changed.
  */