diff --git a/templates/form/select.html.twig b/templates/form/select.html.twig
index 4042ab97d9af9e7ecf98809daadf00d568f62068..18ce6dd3b0a024ec69783f2191ac44f625eff237 100644
--- a/templates/form/select.html.twig
+++ b/templates/form/select.html.twig
@@ -12,13 +12,13 @@
  * @ingroup themeable
  */
 #}
- {# look at the options array and if < 4 then use for the size attribute #}
- {% if options|length < 4 %}
-  {% set select_size = options|length %}
- {% endif %}
+{# if size is not set, look at the options array and if < 4 then use for the size attribute #}
+{% if not attributes.size and options|length < 4 %}
+  {% set attributes = attributes.setAttribute('size', options|length) %}
+{% endif %}
 
 {% apply spaceless %}
-  <select{{ attributes.setAttribute('size', select_size) }}>
+  <select{{ attributes }}>
     {% for option in options %}
       {% if option.type == 'optgroup' %}
         <optgroup label="{{ option.label }}">