diff --git a/includes/install.inc b/includes/install.inc
index 3631c36..6191921 100644
--- a/includes/install.inc
+++ b/includes/install.inc
@@ -657,6 +657,14 @@ function drupal_rewrite_settings($settings = array(), $prefix = '') {
   else {
     throw new Exception(st('Failed to open %settings. Verify the file permissions.', array('%settings' => $default_settings)));
   }
+
+  // Clear opcode cache.
+  if (function_exists('opcache_invalidate')) {
+    opcache_invalidate(DRUPAL_ROOT . '/' . $settings_file);
+  }
+  if (function_exists('apc_delete_file')) {
+    apc_delete_file(DRUPAL_ROOT . '/' . $settings_file);
+  }
 }
 
 /**