diff --git a/modules/cart/commerce_cart.module b/modules/cart/commerce_cart.module
index 5bdd8d4..cf6620c 100644
--- a/modules/cart/commerce_cart.module
+++ b/modules/cart/commerce_cart.module
@@ -1651,7 +1651,16 @@ function commerce_cart_add_to_cart_form($form, &$form_state, $line_item, $show_q
             // Get the options properties from the options module and store the
             // options for the instance in select list format in the array of
             // qualifying fields.
-            $properties = _options_properties('select', FALSE, TRUE, TRUE);
+            // Modules can define widget types for the attribute field that are
+            // unknown to the options module. If this is the case, default to
+            // the select widget restrictions.
+            if (in_array($instance['widget']['type'], array('options_select', 'options_buttons', 'options_onoff'))) {
+              $widget_type = str_replace('options_', '', $instance['widget']['type']);
+            }
+            else {
+              $widget_type = 'select';
+            }
+            $properties = _options_properties($widget_type, FALSE, TRUE, TRUE);
 
             // Try to fetch localized names.
             $allowed_values = NULL;