diff --git a/plugins/platforms/x11/windowed/x11windowed_output.h b/plugins/platforms/x11/windowed/x11windowed_output.h
--- a/plugins/platforms/x11/windowed/x11windowed_output.h
+++ b/plugins/platforms/x11/windowed/x11windowed_output.h
@@ -45,8 +45,6 @@
     explicit X11WindowedOutput(X11WindowedBackend *backend);
     ~X11WindowedOutput() override;
 
-    void init(const QPoint &logicalPosition, const QSize &pixelSize);
-
     xcb_window_t window() const {
         return m_window;
     }
@@ -67,14 +65,17 @@
     void setGeometry(const QPoint &logicalPosition, const QSize &pixelSize);
 
 private:
+    void init(const QPoint &logicalPosition, const QSize &pixelSize);
     void initXInputForWindow();
 
     xcb_window_t m_window = XCB_WINDOW_NONE;
     NETWinInfo *m_winInfo = nullptr;
 
     QPoint m_hostPosition;
 
     X11WindowedBackend *m_backend;
+
+    friend class X11WindowedBackend;
 };
 
 }