diff --git a/src/BladeRouteGenerator.php b/src/BladeRouteGenerator.php
index 1775a6e0..9a9bc703 100644
--- a/src/BladeRouteGenerator.php
+++ b/src/BladeRouteGenerator.php
@@ -9,7 +9,7 @@ class BladeRouteGenerator
 {
     public static $generated;
 
-    public function generate($group = null, string $nonce = null): string
+    public function generate($group = null, ?string $nonce = null): string
     {
         $ziggy = new Ziggy($group);