diff --git a/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php b/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
index b63dc5c85e665..7dad0136ad611 100644
--- a/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
+++ b/src/Symfony/Component/Routing/Loader/AnnotationClassLoader.php
@@ -205,7 +205,8 @@ protected function addRoute(RouteCollection $collection, object $annot, array $g
             }
             foreach ($paths as $locale => $path) {
                 if (preg_match(sprintf('/\{%s(?:<.*?>)?\}/', preg_quote($param->name)), $path)) {
-                    $defaults[$param->name] = $param->getDefaultValue();
+                    $defaultValue = $param->getDefaultValue();
+                    $defaults[$param->name] = $defaultValue instanceof \BackedEnum ? $defaultValue->value : $defaultValue;
                     break;
                 }
             }