diff --git a/sites/default/settings.pantheon.php b/sites/default/settings.pantheon.php
index d4ae35b08..879018271 100644
--- a/sites/default/settings.pantheon.php
+++ b/sites/default/settings.pantheon.php
@@ -58,6 +58,7 @@ if (isset($_ENV['PANTHEON_ENVIRONMENT'])) {
  *
  */
 if (isset($_ENV['PANTHEON_ENVIRONMENT']) && (substr($_SERVER['SCRIPT_NAME'],0,17) != '/core/install.php') && (!is_dir(__DIR__ . '/files/styles'))) {
+  include_once __DIR__ . '/../../core/includes/install.core.inc';
   include_once __DIR__ . '/../../core/includes/install.inc';
   install_goto('core/install.php');
 }