diff --git a/reference/configuration/kernel.rst b/reference/configuration/kernel.rst
index 1c57afed784..f61f52fcc35 100644
--- a/reference/configuration/kernel.rst
+++ b/reference/configuration/kernel.rst
@@ -33,7 +33,7 @@ charset::
 
     class Kernel extends BaseKernel
     {
-        public function getCharset()
+        public function getCharset(): string
         {
             return 'ISO-8859-1';
         }