--- Libc/Libc-262.2.12/mach/headers/Makefile.inc
+++ Libc/Libc-391/mach/headers/Makefile.inc
@@ -4,5 +4,7 @@
                  mach_interface.h \
                  port_obj.h \
                  sync.h \
+                 task.h \
+                 thread_act.h \
                  vm_task.h
 MACH_INSTHDRS := ${MACH_INSTHDRS:S/^/${.CURDIR}\/mach\/headers\//}