diff --git a/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigLoaderPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigLoaderPass.php
index 940e2dc..fee8ed4 100644
--- a/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigLoaderPass.php
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigLoaderPass.php
@@ -45,7 +45,9 @@ public function process(ContainerBuilder $container) {
 
       // Sort the loaders by priority. Lower priority loaders are loaded later.
       foreach ($loaderIds as $id => $attributes) {
-        $priorities[$id] = isset($attributes[0]['priority']) ? $attributes[0]['priority'] : 0;
+        foreach ($attributes as $attribute) {
+          $priorities[$id] = isset($attribute['priority']) ? $attribute['priority'] : 0;
+        }
         $loaders[$id] = $container->getDefinition($id);
       }
       array_multisort($priorities, SORT_DESC, $loaders);