--- Gnu-Mach/ipc/mach_rpc.c	2020/09/02 04:36:56	1.1.1.1
+++ Gnu-Mach/ipc/mach_rpc.c	2020/09/02 04:45:06	1.1.1.2
@@ -21,6 +21,7 @@
 
 #ifdef MIGRATING_THREADS
 
+#include <kern/printf.h>
 #include <mach/kern_return.h>
 #include <mach/port.h>
 #include <mach/rpc.h>