diff --git a/lib/outputrequirementslib.php b/lib/outputrequirementslib.php
index f7577d9e764..fec29879d9f 100644
--- a/lib/outputrequirementslib.php
+++ b/lib/outputrequirementslib.php
@@ -1618,7 +1618,7 @@ class YUI_config {
         }
 
         $cache = cache::make('core', 'yuimodules');
-        if ($CFG->jsrev == -1) {
+        if (!isset($CFG->jsrev) || $CFG->jsrev == -1) {
             $metadata = array();
             $cache->delete('metadata');
         } else {