diff --git a/core/lib/Drupal/Core/Cache/MutableCacheableDependencyInterface.php b/core/lib/Drupal/Core/Cache/MutableCacheableDependencyInterface.php
index acfe5f6..978a604 100644
--- a/core/lib/Drupal/Core/Cache/MutableCacheableDependencyInterface.php
+++ b/core/lib/Drupal/Core/Cache/MutableCacheableDependencyInterface.php
@@ -45,6 +45,9 @@ public function addCacheTags(array $cache_tags);
    *   The max age to associate.
    *
    * @return $this
+   *
+   * @throws \InvalidArgumentException
+   *   Thrown if a non-integer value is supplied.
    */
   public function setCacheMaxAgeIfLower($max_age);
 
diff --git a/core/lib/Drupal/Core/Cache/MutableCacheableDependencyTrait.php b/core/lib/Drupal/Core/Cache/MutableCacheableDependencyTrait.php
index 8d33b55..3b64be2 100644
--- a/core/lib/Drupal/Core/Cache/MutableCacheableDependencyTrait.php
+++ b/core/lib/Drupal/Core/Cache/MutableCacheableDependencyTrait.php
@@ -13,9 +13,9 @@
 trait MutableCacheableDependencyTrait {
 
   /**
-   * Runtime cache contexts.
+   * Cache contexts.
    *
-   * @var array
+   * @var string[]
    */
   protected $cacheContexts = [];