diff --git a/core/modules/system/lib/Drupal/system/Plugin/Block/SystemHelpBlock.php b/core/modules/system/lib/Drupal/system/Plugin/Block/SystemHelpBlock.php
index dd38073..994bf2b 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/Block/SystemHelpBlock.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/Block/SystemHelpBlock.php
@@ -78,6 +78,10 @@ public static function create(ContainerInterface $container, array $configuratio
    * {@inheritdoc}
    */
   public function access(AccountInterface $account) {
+    $exception = $this->request->attributes->get('exception');
+    if ($exception && in_array($exception->getStatusCode(), array(403, 404))) {
+      return FALSE;
+    }
     $this->help = $this->getActiveHelp($this->request);
     return (bool) $this->help;
   }
@@ -94,7 +98,7 @@ protected function getActiveHelp(Request $request) {
     $arg = drupal_help_arg(explode('/', $request->attributes->get('_system_path')));
 
     foreach ($this->moduleHandler->getImplementations('help') as $module) {
-      $router_path = current_path();
+      $router_path = trim($request->getPathInfo(), '/');
       $function = $module . '_help';
       // Lookup help for this path.
       if ($help = $function($router_path, $arg)) {