diff --git a/index.php b/index.php
index 32aa537..708a9e3 100644
--- a/index.php
+++ b/index.php
@@ -79,7 +79,7 @@ else
 
 ///// template starts here /////
 header('Content-Type: text/html; charset=utf-8');
-header('Expires: '.gmdate('D, d M Y H:i:s \G\M\T', time() + 3600));
+header('Cache-Control: max-age=3600');
 
 require 'template.php';
 
diff --git a/plugins/viewer/view.php b/plugins/viewer/view.php
index 9ccf5cd..4b2eddd 100644
--- a/plugins/viewer/view.php
+++ b/plugins/viewer/view.php
@@ -77,7 +77,7 @@ $firefox = strpos($_SERVER['HTTP_USER_AGENT'], 'Firefox') !== false;
 
 ///// template starts here /////
 header('Content-Type: text/html; charset=utf-8');
-header('Expires: '.gmdate('D, d M Y H:i:s \G\M\T', time() + 3600));
+header('Cache-Control: max-age=3600');
 
 require 'template.php';