diff --git a/src/plugins/platforms/cocoa/qcocoawindow.h b/src/plugins/platforms/cocoa/qcocoawindow.h
index 3b5be0af0f..324a43c8ae 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.h
+++ b/src/plugins/platforms/cocoa/qcocoawindow.h
@@ -49,7 +49,8 @@
 
 #include "qcocoaglcontext.h"
 #include "qnsview.h"
-class QT_PREPEND_NAMESPACE(QCocoaWindow);
+
+QT_FORWARD_DECLARE_CLASS(QCocoaWindow)
 
 @interface QNSWindow : NSWindow {
     @public QCocoaWindow *m_cocoaPlatformWindow;