diff --git a/includes/theme.inc b/includes/theme.inc
index a696117cf86fc5b499c1b221a1516baeec4c5f0d..f5731693f60bd3ec9d56b787b8e9645a40b23bf3 100644
--- a/includes/theme.inc
+++ b/includes/theme.inc
@@ -95,8 +95,8 @@ function drupal_theme_initialize() {
   $base_theme = array();
   $ancestor = $theme;
   while ($ancestor && isset($themes[$ancestor]->base_theme)) {
-    $base_theme[] = $new_base_theme = $themes[$themes[$ancestor]->base_theme];
     $ancestor = $themes[$ancestor]->base_theme;
+    $base_theme[] = $themes[$ancestor];
   }
   _drupal_theme_initialize($themes[$theme], array_reverse($base_theme));