diff --git a/interface.go b/interface.go
index bf79f0f..610578d 100644
--- a/interface.go
+++ b/interface.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"errors"
 	"io"
-	"net"
 	"os"
 	"runtime"
 	"sync/atomic"
@@ -16,24 +15,16 @@ import (
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/firewall"
 	"github.com/slackhq/nebula/iputil"
+	"github.com/slackhq/nebula/overlay"
 	"github.com/slackhq/nebula/udp"
 )
 
 const mtu = 9001
 
-type Inside interface {
-	io.ReadWriteCloser
-	Activate() error
-	CidrNet() *net.IPNet
-	DeviceName() string
-	WriteRaw([]byte) error
-	NewMultiQueueReader() (io.ReadWriteCloser, error)
-}
-
 type InterfaceConfig struct {
 	HostMap                 *HostMap
 	Outside                 *udp.Conn
-	Inside                  Inside
+	Inside                  overlay.Device
 	certState               *CertState
 	Cipher                  string
 	Firewall                *Firewall
@@ -57,7 +48,7 @@ type InterfaceConfig struct {
 type Interface struct {
 	hostMap            *HostMap
 	outside            *udp.Conn
-	inside             Inside
+	inside             overlay.Device
 	certState          *CertState
 	cipher             string
 	firewall           *Firewall
diff --git a/main.go b/main.go
index 8dc9536..2d62176 100644
--- a/main.go
+++ b/main.go
@@ -10,6 +10,7 @@ import (
 	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/iputil"
+	"github.com/slackhq/nebula/overlay"
 	"github.com/slackhq/nebula/sshd"
 	"github.com/slackhq/nebula/udp"
 	"github.com/slackhq/nebula/util"
@@ -137,7 +138,7 @@ func Main(c *config.C, configTest bool, buildVersion string, logger *logrus.Logg
 		l.WithField("duration", conntrackCacheTimeout).Info("Using routine-local conntrack cache")
 	}
 
-	var tun Inside
+	var tun overlay.Device
 	if !configTest {
 		c.CatchHUP(ctx)
 
diff --git a/overlay/device.go b/overlay/device.go
new file mode 100644
index 0000000..24037af
--- /dev/null
+++ b/overlay/device.go
@@ -0,0 +1,15 @@
+package overlay
+
+import (
+	"io"
+	"net"
+)
+
+type Device interface {
+	io.ReadWriteCloser
+	Activate() error
+	CidrNet() *net.IPNet
+	DeviceName() string
+	WriteRaw([]byte) error
+	NewMultiQueueReader() (io.ReadWriteCloser, error)
+}
diff --git a/tun_windows.go b/tun_windows.go
index 5c73459..d55ae5f 100644
--- a/tun_windows.go
+++ b/tun_windows.go
@@ -13,10 +13,11 @@ import (
 	"syscall"
 
 	"github.com/sirupsen/logrus"
+	"github.com/slackhq/nebula/overlay"
 )
 
 type Tun struct {
-	Inside
+	overlay.Device
 }
 
 func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int) (ifce *Tun, err error) {
@@ -34,7 +35,7 @@ func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int
 		useWintun = false
 	}
 
-	var inside Inside
+	var inside overlay.Device
 	if useWintun {
 		inside, err = newWinTun(deviceName, cidr, defaultMTU, unsafeRoutes, txQueueLen)
 		if err != nil {
@@ -48,7 +49,7 @@ func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int
 	}
 
 	return &Tun{
-		Inside: inside,
+		Device: inside,
 	}, nil
 }