diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index bc6af1f..3582bd2 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -550,7 +550,7 @@ function drupal_get_filename($type, $name, $filename = NULL) {
  */
 function variable_init($conf = array()) {
   // NOTE: caching the variables improves performance by 20% when serving cached pages.
-  if ($cached = cache_get('variables', 'cache')) {
+  if (($cached = cache_get('variables', 'cache')) && !empty($cached->data)) {
     $variables = $cached->data;
   }
   else {