core/lib/Drupal/Core/Cache/CacheableMetadata.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/lib/Drupal/Core/Cache/CacheableMetadata.php b/core/lib/Drupal/Core/Cache/CacheableMetadata.php
index a0ec249..1bd01a5 100644
--- a/core/lib/Drupal/Core/Cache/CacheableMetadata.php
+++ b/core/lib/Drupal/Core/Cache/CacheableMetadata.php
@@ -170,7 +170,7 @@ public function merge(CacheableMetadata $other) {
       $result->maxAge = $this->maxAge;
     }
     else {
-      Cache::mergeMaxAges($this->maxAge, $other->maxAge);
+      $result->maxAge = Cache::mergeMaxAges($this->maxAge, $other->maxAge);
     }
     return $result;
   }