diff --git a/unix/mkall.sh b/unix/mkall.sh
index d257fac5..d727cad1 100755
--- a/unix/mkall.sh
+++ b/unix/mkall.sh
@@ -199,7 +199,7 @@ illumos_amd64)
         mksyscall="go run mksyscall_solaris.go"
 	mkerrors=
 	mksysnum=
-	mktypes=
+	mktypes="GOARCH=$GOARCH go tool cgo -godefs"
 	;;
 *)
 	echo 'unrecognized $GOOS_$GOARCH: ' "$GOOSARCH" 1>&2
diff --git a/unix/types_illumos.go b/unix/types_illumos.go
new file mode 100644
index 00000000..a4860c77
--- /dev/null
+++ b/unix/types_illumos.go
@@ -0,0 +1,47 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+// +build ignore
+
+/*
+Input to cgo -godefs.  See README.md
+*/
+
+package unix
+
+/*
+#include <net/if.h>
+#include <sys/sockio.h>
+#include <sys/stropts.h>
+
+// Many illumos distributions ship a 3rd party tun/tap driver
+// from https://github.com/kaizawa/tuntap
+// It supports a pair of IOCTLs defined at
+// https://github.com/kaizawa/tuntap/blob/master/if_tun.h#L91-L93
+#define TUNNEWPPA	(('T'<<16) | 0x0001)
+#define TUNSETPPA	(('T'<<16) | 0x0002)
+*/
+import "C"
+
+const (
+	TUNNEWPPA = C.TUNNEWPPA
+	TUNSETPPA = C.TUNSETPPA
+
+	// sys/stropts.h:
+	I_STR     = C.I_STR
+	I_POP     = C.I_POP
+	I_PUSH    = C.I_PUSH
+	I_PLINK   = C.I_PLINK
+	I_PUNLINK = C.I_PUNLINK
+
+	// sys/sockio.h:
+	IF_UNITSEL = C.IF_UNITSEL
+)
+
+type strbuf C.struct_strbuf
+
+type strioctl C.struct_strioctl
+
+type lifreq C.struct_lifreq
diff --git a/unix/ztypes_illumos_amd64.go b/unix/ztypes_illumos_amd64.go
new file mode 100644
index 00000000..1137a5a1
--- /dev/null
+++ b/unix/ztypes_illumos_amd64.go
@@ -0,0 +1,40 @@
+// cgo -godefs types_illumos.go | go run mkpost.go
+// Code generated by the command above; see README.md. DO NOT EDIT.
+
+//go:build amd64 && illumos
+// +build amd64,illumos
+
+package unix
+
+const (
+	TUNNEWPPA = 0x540001
+	TUNSETPPA = 0x540002
+
+	I_STR     = 0x5308
+	I_POP     = 0x5303
+	I_PUSH    = 0x5302
+	I_PLINK   = 0x5316
+	I_PUNLINK = 0x5317
+
+	IF_UNITSEL = -0x7ffb8cca
+)
+
+type strbuf struct {
+	Maxlen int32
+	Len    int32
+	Buf    *int8
+}
+
+type strioctl struct {
+	Cmd    int32
+	Timout int32
+	Len    int32
+	Dp     *int8
+}
+
+type lifreq struct {
+	Name   [32]int8
+	Lifru1 [4]byte
+	Type   uint32
+	Lifru  [336]byte
+}