diff --git a/internal/openvpn/auth.go b/internal/openvpn/auth.go
index ebd46bce..54d57fda 100644
--- a/internal/openvpn/auth.go
+++ b/internal/openvpn/auth.go
@@ -6,6 +6,10 @@ import (
 	"strings"
 )
 
+type AuthWriter interface {
+	WriteAuthFile(user, password string, puid, pgid int) error
+}
+
 // WriteAuthFile writes the OpenVPN auth file to disk with the right permissions.
 func (c *configurator) WriteAuthFile(user, password string, puid, pgid int) error {
 	file, err := os.Open(c.authFilePath)
diff --git a/internal/openvpn/command.go b/internal/openvpn/command.go
index b7397188..8c073640 100644
--- a/internal/openvpn/command.go
+++ b/internal/openvpn/command.go
@@ -18,6 +18,11 @@ const (
 	binOpenvpn25 = "openvpn"
 )
 
+type Starter interface {
+	Start(ctx context.Context, version string, flags []string) (
+		stdoutLines, stderrLines chan string, waitError chan error, err error)
+}
+
 func (c *configurator) Start(ctx context.Context, version string, flags []string) (
 	stdoutLines, stderrLines chan string, waitError chan error, err error) {
 	var bin string
@@ -40,6 +45,11 @@ func (c *configurator) Start(ctx context.Context, version string, flags []string
 	return c.cmder.Start(cmd)
 }
 
+type VersionGetter interface {
+	Version24(ctx context.Context) (version string, err error)
+	Version25(ctx context.Context) (version string, err error)
+}
+
 func (c *configurator) Version24(ctx context.Context) (version string, err error) {
 	return c.version(ctx, binOpenvpn24)
 }
diff --git a/internal/openvpn/loop.go b/internal/openvpn/loop.go
index dc9d7cbb..c2c7b2cb 100644
--- a/internal/openvpn/loop.go
+++ b/internal/openvpn/loop.go
@@ -36,7 +36,7 @@ type Loop struct {
 	pgid           int
 	targetConfPath string
 	// Configurators
-	conf    Configurator
+	conf    StarterAuthWriter
 	fw      firewall.Configurator
 	routing routing.Routing
 	// Other objects
diff --git a/internal/openvpn/openvpn.go b/internal/openvpn/openvpn.go
index c8bae346..6dbf70e6 100644
--- a/internal/openvpn/openvpn.go
+++ b/internal/openvpn/openvpn.go
@@ -3,8 +3,6 @@
 package openvpn
 
 import (
-	"context"
-
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/unix"
 	"github.com/qdm12/golibs/command"
@@ -12,13 +10,15 @@ import (
 )
 
 type Configurator interface {
-	Version24(ctx context.Context) (version string, err error)
-	Version25(ctx context.Context) (version string, err error)
-	WriteAuthFile(user, password string, puid, pgid int) error
-	CheckTUN() error
-	CreateTUN() error
-	Start(ctx context.Context, version string, flags []string) (
-		stdoutLines, stderrLines chan string, waitError chan error, err error)
+	VersionGetter
+	AuthWriter
+	TUNCheckCreater
+	Starter
+}
+
+type StarterAuthWriter interface {
+	Starter
+	AuthWriter
 }
 
 type configurator struct {
diff --git a/internal/openvpn/tun.go b/internal/openvpn/tun.go
index 3c79185c..70543e46 100644
--- a/internal/openvpn/tun.go
+++ b/internal/openvpn/tun.go
@@ -8,6 +8,15 @@ import (
 	"github.com/qdm12/gluetun/internal/unix"
 )
 
+type TUNCheckCreater interface {
+	TUNChecker
+	TUNCreater
+}
+
+type TUNChecker interface {
+	CheckTUN() error
+}
+
 // CheckTUN checks the tunnel device is present and accessible.
 func (c *configurator) CheckTUN() error {
 	c.logger.Info("checking for device " + c.tunDevPath)
@@ -21,6 +30,10 @@ func (c *configurator) CheckTUN() error {
 	return nil
 }
 
+type TUNCreater interface {
+	CreateTUN() error
+}
+
 func (c *configurator) CreateTUN() error {
 	c.logger.Info("creating " + c.tunDevPath)