diff --git a/includes/pre-render.inc b/includes/pre-render.inc
index 59d0e70..b9ab015 100644
--- a/includes/pre-render.inc
+++ b/includes/pre-render.inc
@@ -18,6 +18,7 @@ function _bootstrap_pre_render_input($element) {
     'select',
     'textarea',
     'textfield',
+    'machine_name',
     // HTML5.
     'email',
     // Webform module.