diff -Nurp VirtualBox-4.3.16.orig/src/VBox/Additions/common/VBoxGuestLib/Makefile.kmk VirtualBox-4.3.16/src/VBox/Additions/common/VBoxGuestLib/Makefile.kmk
--- VirtualBox-4.3.16.orig/src/VBox/Additions/common/VBoxGuestLib/Makefile.kmk	2014-09-09 22:46:56.000000000 +0300
+++ VirtualBox-4.3.16/src/VBox/Additions/common/VBoxGuestLib/Makefile.kmk	2014-09-12 11:06:10.044776710 +0300
@@ -39,10 +39,12 @@ LIBRARIES += \
 	VBoxGuestR3Lib \
 	VBoxGuestR3LibShared
 ifndef VBOX_ONLY_TESTSUITE
+ifndef VBOX_USE_SYSTEM_XORG_HEADERS
  if1of ($(KBUILD_TARGET), freebsd linux netbsd openbsd)
   LIBRARIES += \
   	VBoxGuestR3LibXFree86
  endif
+endif
  if1of ($(KBUILD_TARGET), freebsd linux netbsd openbsd solaris)
   LIBRARIES += \
   	VBoxGuestR3LibXOrg