diff --git a/book/forms.rst b/book/forms.rst
index 384cc9cbd8e..29235ee13b3 100644
--- a/book/forms.rst
+++ b/book/forms.rst
@@ -242,7 +242,7 @@ controller::
 
         $form->handleRequest($request);
 
-        if ($form->isValid()) {
+        if ($form->isSubmitted() && $form->isValid()) {
             // ... perform some action, such as saving the task to the database
 
             return $this->redirectToRoute('task_success');