Index: /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIFrameBuffer.cpp
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIFrameBuffer.cpp	(revision 51694)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/runtime/UIFrameBuffer.cpp	(revision 51695)
@@ -274,5 +274,8 @@
     Q_UNUSED(uHeight);
     Q_UNUSED(image); // by ComSafeArrayIn
+#ifdef VBOX_WITH_XPCOM
     Q_UNUSED(imageSize); // by ComSafeArrayIn
+#endif /* VBOX_WITH_XPCOM */
+
     return E_NOTIMPL;
 }