--- src/VBox/Frontends/VBoxSDL/Makefile.kmk.orig	2020-07-10 02:56:34.000000000 +1000
+++ src/VBox/Frontends/VBoxSDL/Makefile.kmk	2020-08-23 11:20:54.811506000 +1000
@@ -58,6 +58,7 @@
   VBoxSDL_DEFS    += VBOX_SECURELABEL
  endif
 endif
+VBoxSDL_DEFS.bsdsunix = VBOXSDL_WITH_X11
 VBoxSDL_DEFS.freebsd = VBOXSDL_WITH_X11
 VBoxSDL_DEFS.linux = _GNU_SOURCE VBOXSDL_WITH_X11
 VBoxSDL_DEFS.solaris = VBOXSDL_WITH_X11
@@ -70,7 +71,7 @@
 VBoxSDL_INCS = \
 	$(VBoxSDL_0_OUTDIR) \
 	$(VBOX_GRAPHICS_INCS)
-ifeq ($(filter-out freebsd linux netbsd openbsd solaris,$(KBUILD_TARGET)),) # X11
+ifeq ($(filter-out bsdsunix freebsd linux netbsd openbsd solaris,$(KBUILD_TARGET)),) # X11
 VBoxSDL_INCS += \
 	$(VBOX_XCURSOR_INCS)
 endif
@@ -79,7 +80,7 @@
 VBoxSDL_LIBS = \
 	$(LIB_SDK_LIBSDL_SDLMAIN)
 endif
-ifeq ($(filter-out freebsd linux netbsd openbsd solaris,$(KBUILD_TARGET)),) # X11
+ifeq ($(filter-out bsdsunix freebsd linux netbsd openbsd solaris,$(KBUILD_TARGET)),) # X11
 VBoxSDL_LIBS += \
 	$(PATH_STAGE_DLL)/VBoxKeyboard$(VBOX_SUFF_DLL) \
 	$(VBOX_XCURSOR_LIBS) \
@@ -137,7 +138,7 @@
 ifdef VBOX_OPENGL
 tstSDL_LIBS.linux += GL
 endif
-ifeq ($(filter-out freebsd linux netbsd openbsd solaris,$(KBUILD_TARGET)),) # X11
+ifeq ($(filter-out bsdsunix freebsd linux netbsd openbsd solaris,$(KBUILD_TARGET)),) # X11
 tstSDL_LIBPATH = \
 	$(VBOX_LIBPATH_X11)
 endif