diff --git a/kernel/arch/i386/arch_system.c b/kernel/arch/i386/arch_system.c
index 5148cd606..146df9267 100644
--- a/kernel/arch/i386/arch_system.c
+++ b/kernel/arch/i386/arch_system.c
@@ -17,6 +17,7 @@
 #include <machine/vm.h>
 
 #include <sys/sigcontext.h>
+#include <minix/u64.h>
 
 #include "archconst.h"
 #include "arch_proto.h"