Index: desktop/Executable_oosplash.mk
--- desktop/Executable_oosplash.mk.orig
+++ desktop/Executable_oosplash.mk
@@ -23,6 +23,11 @@ $(eval $(call gb_Executable_add_cobjects,oosplash,\
     desktop/unx/source/start \
 ))
 
+$(eval $(call gb_Executable_set_include,oosplash,\
+    $$(INCLUDE) \
+    -I/usr/X11R6/include \
+))
+
 ifneq ($(USE_XINERAMA),)
 
 $(eval $(call gb_Executable_add_defs,oosplash,\