diff --git modules/system/system.admin.inc modules/system/system.admin.inc
index 263b063..752e45f 100644
--- modules/system/system.admin.inc
+++ modules/system/system.admin.inc
@@ -1647,6 +1647,9 @@ function system_performance_settings() {
     '#title' => t('Expiration of cached pages'),
     '#default_value' => variable_get('page_cache_maximum_age', 0),
     '#options' => $period,
+    // This setting has no effect unless 'page_cache_invoke_hooks' is FALSE,
+    // so we hide it when it is not relevant.
+    '#access' => !variable_get('page_cache_invoke_hooks', TRUE),
     '#description' => t('The maximum time an external cache can use an old version of a page.')
   );