diff --git a/core/lib/Drupal/Core/Ajax/CssCommand.php b/core/lib/Drupal/Core/Ajax/CssCommand.php
index 470d583d7b0fc885b1b1e58613d4dc9aac370946..aba95d7ed812fd12185e30b058e7b1def67da284 100644
--- a/core/lib/Drupal/Core/Ajax/CssCommand.php
+++ b/core/lib/Drupal/Core/Ajax/CssCommand.php
@@ -61,6 +61,8 @@ public function __construct($selector, array $css = array()) {
    *   The CSS property to be changed.
    * @param $value
    *   The new value of the CSS property.
+   *
+   * @return $this
    */
   public function setProperty($property, $value) {
     $this->css[$property] = $value;
diff --git a/core/lib/Drupal/Core/Asset/CssOptimizer.php b/core/lib/Drupal/Core/Asset/CssOptimizer.php
index 1090d5aefdd58b09a6ddda2566dd665ca49ff767..b93a638f9e41794f1b25c2177522ce4460b12dc4 100644
--- a/core/lib/Drupal/Core/Asset/CssOptimizer.php
+++ b/core/lib/Drupal/Core/Asset/CssOptimizer.php
@@ -124,6 +124,7 @@ public function loadFile($file, $optimize = NULL, $reset_basepath = TRUE) {
    * @param array $matches
    *   An array of matches by a preg_replace_callback() call that scans for
    *   @import-ed CSS files, except for external CSS files.
+   *
    * @return
    *   The contents of the CSS file at $matches[1], with corrected paths.
    *
@@ -220,6 +221,9 @@ protected function processCss($contents, $optimize = FALSE) {
    * Note: the only reason this method is public is so color.module can call it;
    * it is not on the AssetOptimizerInterface, so future refactorings can make
    * it protected.
+   *
+   * @return string
+   *   The file path.
    */
   public function rewriteFileURI($matches) {
     // Prefix with base and remove '../' segments where possible.