Index: uspace/lib/display/include/types/display.h
===================================================================
--- uspace/lib/display/include/types/display.h	(revision 6c2aba3fef6f293d95c6f25efe30068d7cf8a73f)
+++ uspace/lib/display/include/types/display.h	(revision 2a515dcdbf45d99dae90d9f82bc03f8416d806b7)
@@ -40,5 +40,9 @@
 #include <io/kbd_event.h>
 #include <io/pos_event.h>
+#include <stddef.h>
 #include <stdint.h>
+
+/** Use the default display service (argument to display_open() */
+#define DISPLAY_DEFAULT NULL
 
 /** Display server session */