diff --git a/client.h b/client.h
index f624ea0267..8f49c36204 100644
--- a/client.h
+++ b/client.h
@@ -172,9 +172,8 @@ class Client
     Q_PROPERTY(bool transient READ isTransient NOTIFY transientChanged)
     /**
      * The Client to which this Client is a transient if any.
-     * Property uses a QObject. If the property is needed as a Client, perform a qobject_cast.
      **/
-    Q_PROPERTY(QObject *transientFor READ transientFor NOTIFY transientChanged)
+    Q_PROPERTY(KWin::Client *transientFor READ transientFor NOTIFY transientChanged)
     /**
      * By how much the window wishes to grow/shrink at least. Usually QSize(1,1).
      * MAY BE DISOBEYED BY THE WM! It's only for information, do NOT rely on it at all.
@@ -1169,5 +1168,6 @@ KWIN_COMPARE_PREDICATE(WrapperIdMatchPredicate, Client, Window, cl->wrapperId()
 KWIN_COMPARE_PREDICATE(InputIdMatchPredicate, Client, Window, cl->inputId() == value);
 
 } // namespace
+Q_DECLARE_METATYPE(KWin::Client*)
 
 #endif