diff --git a/internal/db/db.go b/internal/db/db.go
index 9d65db0..ef63108 100644
--- a/internal/db/db.go
+++ b/internal/db/db.go
@@ -8,7 +8,7 @@ type DB interface {
 	GetUser(id string) (*api.User, error)
 
 	// Devices.
-	PutDevice(pubKey, userId string) (string, error)
+	PutDevice(pubKey []byte, userId string) (string, error)
 	GetDevice(id string) (*api.Device, error)
 	GetUserDevices(userId string) ([]*api.Device, error)
 	GetDeviceUser(deviceId string) (*api.User, error)
diff --git a/internal/db/local.go b/internal/db/local.go
index 840d699..2ee60b5 100644
--- a/internal/db/local.go
+++ b/internal/db/local.go
@@ -43,7 +43,7 @@ func (d *localDB) GetUser(id string) (*api.User, error) {
 	return u, nil
 }
 
-func (d *localDB) PutDevice(pubKey, userId string) (string, error) {
+func (d *localDB) PutDevice(pubKey []byte, userId string) (string, error) {
 	id := ulid.Make().String()
 	if _, ok := d.users[userId]; !ok {
 		return "", errors.New("user does not exist")