diff --git a/includes/form.inc b/includes/form.inc
index 8ca048a..ac3da95 100644
--- a/includes/form.inc
+++ b/includes/form.inc
@@ -4027,7 +4027,7 @@ function theme_form_element($variables) {
     $attributes['class'][] = 'form-type-' . strtr($element['#type'], '_', '-');
   }
   if (!empty($element['#name'])) {
-    $attributes['class'][] = 'form-item-' . strtr($element['#name'], array(' ' => '-', '_' => '-', '[' => '-', ']' => ''));
+    $attributes['class'][] = 'form-item-' . strtr($element['#name'], array(' ' => '-', '_' => '-', '.' => '-', ':' => '-', '[' => '-', ']' => ''));
   }
   // Add a class for disabled elements to facilitate cross-browser styling.
   if (!empty($element['#attributes']['disabled'])) {