diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3a223514..23dfb133 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@ Please also have a look at our
 
 ### Changed
 
+- Mark `Selector::isValid()` as `@internal` (#1037)
 - Mark parsing-related methods of most CSS elements as `@internal` (#908)
 - Mark `OutputFormat::nextLevel()` as `@internal` (#901)
 - Only allow `string` for some `OutputFormat` properties (#885)
diff --git a/src/Property/Selector.php b/src/Property/Selector.php
index 63080a6a..9f9a22dd 100644
--- a/src/Property/Selector.php
+++ b/src/Property/Selector.php
@@ -78,6 +78,8 @@ class Selector
      * @param string $selector
      *
      * @return bool
+     *
+     * @internal since V8.8.0
      */
     public static function isValid($selector)
     {