diff --git a/src/HorizontalFormBuilder.php b/src/HorizontalFormBuilder.php
index cc2fd46748c96231d0f53ce1ea00d23852b5c079..9e3807d73a9c2e36166bc44e3ab58a3c2c2c3256 100644
--- a/src/HorizontalFormBuilder.php
+++ b/src/HorizontalFormBuilder.php
@@ -109,7 +109,7 @@ class HorizontalFormBuilder extends BasicFormBuilder
         return $checkGroup;
     }
 
-    public function radio(string $label, string $name, int|string $value = null): OffsetFormGroup
+    public function radio(string $label, string $name, int|string|null $value = null): OffsetFormGroup
     {
         if (is_null($value)) {
             $value = $label;