core/lib/Drupal/Core/Render/Renderer.php | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/core/lib/Drupal/Core/Render/Renderer.php b/core/lib/Drupal/Core/Render/Renderer.php
index 4dd1dba..946d940 100644
--- a/core/lib/Drupal/Core/Render/Renderer.php
+++ b/core/lib/Drupal/Core/Render/Renderer.php
@@ -509,19 +509,15 @@ protected function doRender(&$elements, $is_root_call = FALSE) {
 
     // Only apply the prefix and suffix markup around the children if they have
     // not already been rendered by the theme manager.
-    if (!isset($elements['#render_children'])) {
-      // We store the resulting output in $elements['#markup'], to be
-      // consistent with how render cached output gets stored. This ensures that
-      // placeholder replacement logic gets the same data to work with, no
-      // matter if #cache is disabled, #cache is enabled, there is a cache hit
-      // or miss.
-      $prefix = isset($elements['#prefix']) ? $this->xssFilterAdminIfUnsafe($elements['#prefix']) : '';
-      $suffix = isset($elements['#suffix']) ? $this->xssFilterAdminIfUnsafe($elements['#suffix']) : '';
-      $elements['#markup'] = Markup::create($prefix . $elements['#children'] . $suffix);
-    }
-    else {
-      $elements['#markup'] = Markup::create($elements['#children']);
-    }
+    $prefix = !isset($elements['#render_children']) && isset($elements['#prefix']) ? $this->xssFilterAdminIfUnsafe($elements['#prefix']) : '';
+    $suffix = !isset($elements['#render_children']) && isset($elements['#suffix']) ? $this->xssFilterAdminIfUnsafe($elements['#suffix']) : '';
+
+    // We store the resulting output in $elements['#markup'], to be consistent
+    // with how render cached output gets stored. This ensures that placeholder
+    // replacement logic gets the same data to work with, no matter if #cache is
+    // disabled, #cache is enabled, there is a cache hit or miss.
+    $elements['#markup'] = Markup::create($prefix . $elements['#children'] . $suffix);
+
     // We've rendered this element (and its subtree!), now update the context.
     $context->update($elements);