diff --git a/src/widgets/util/qsystemtrayicon_x11.cpp b/src/widgets/util/qsystemtrayicon_x11.cpp
index 29391124c5..07d504e962 100644
--- a/src/widgets/util/qsystemtrayicon_x11.cpp
+++ b/src/widgets/util/qsystemtrayicon_x11.cpp
@@ -182,7 +182,7 @@ QSystemTrayIconSys::QSystemTrayIconSys(QSystemTrayIcon *qIn) :
 
     // Request to be a tray window according to GNOME, NET WM Specification
     static Atom netwm_tray_atom = XInternAtom(display, "_NET_SYSTEM_TRAY_OPCODE", False);
-    long l[5] = { CurrentTime, SYSTEM_TRAY_REQUEST_DOCK, winId(), 0, 0 };
+    long l[5] = { CurrentTime, SYSTEM_TRAY_REQUEST_DOCK, static_cast<long>(winId()), 0, 0 };
     XEvent ev;
     memset(&ev, 0, sizeof(ev));
     ev.xclient.type = ClientMessage;