diff --git a/vendor/golang.org/x/sys/unix/syscall_darwin_amd64.go b/vendor/golang.org/x/sys/unix/syscall_darwin_amd64.go
index 914b89b..5867ed0 100644
--- a/vendor/golang.org/x/sys/unix/syscall_darwin_amd64.go
+++ b/vendor/golang.org/x/sys/unix/syscall_darwin_amd64.go
@@ -10,6 +10,9 @@
 	"syscall"
 )
 
+//sys	sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) = SYS___SYSCTL
+//sys   ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
+
 func setTimespec(sec, nsec int64) Timespec {
 	return Timespec{Sec: sec, Nsec: nsec}
 }
@@ -43,6 +46,10 @@
 	msghdr.Controllen = uint32(length)
 }
 
+func (msghdr *Msghdr) SetIovlen(length int) {
+	msghdr.Iovlen = int32(length)
+}
+
 func (cmsg *Cmsghdr) SetLen(length int) {
 	cmsg.Len = uint32(length)
 }