diff --git a/doc/src/snippets/statemachine/main4.cpp b/doc/src/snippets/statemachine/main4.cpp
index 8c9a8aca0e06c509bb186f13c6e10198b90bd194..5e8d4772dc60d4cd15e7213652c3a44692ee1fe5 100644
--- a/doc/src/snippets/statemachine/main4.cpp
+++ b/doc/src/snippets/statemachine/main4.cpp
@@ -55,12 +55,14 @@ struct StringEvent : public QEvent
 //![1]
 class StringTransition : public QAbstractTransition
 {
+    Q_OBJECT
+
 public:
     StringTransition(const QString &value)
         : m_value(value) {}
 
 protected:
-    virtual bool eventTest(QEvent *e) const
+    virtual bool eventTest(QEvent *e)
     {
         if (e->type() != QEvent::Type(QEvent::User+1)) // StringEvent
             return false;