Index: vcl/Library_desktop_detector.mk
--- vcl/Library_desktop_detector.mk.orig
+++ vcl/Library_desktop_detector.mk
@@ -24,6 +24,7 @@ $(eval $(call gb_Library_set_plugin_for,desktop_detect
 $(eval $(call gb_Library_set_include,desktop_detector,\
     $$(INCLUDE) \
     -I$(SRCDIR)/vcl/inc \
+	-I/usr/X11R6/include \
 ))
 
 $(eval $(call gb_Library_add_defs,desktop_detector,\
