diff --git a/core/misc/collapse.js b/core/misc/collapse.js
index 5622d08..55402c3 100644
--- a/core/misc/collapse.js
+++ b/core/misc/collapse.js
@@ -63,7 +63,7 @@ $.extend(CollapsibleDetails.prototype, {
     $('<span class="details-summary-prefix visually-hidden"></span>')
       .append(this.$node.attr('open') ? Drupal.t('Hide') : Drupal.t('Show'))
       .prependTo($legend)
-      .after(' ');
+      .after(document.createTextNode(' '));
 
     // .wrapInner() does not retain bound events.
     $('<a class="details-title"></a>')