diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..3353ff4
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,6 @@
+module github.com/eduhenke/go-ocpp
+
+require (
+	github.com/google/uuid v1.1.0
+	github.com/sirupsen/logrus v1.3.0
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..233ebdb
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,17 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/google/uuid v1.1.0 h1:Jf4mxPC/ziBnoPIdpQdPJ9OeiomAUHLvxmPRSPH9m4s=
+github.com/google/uuid v1.1.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1 h1:mweAR1A6xJ3oS2pRaGiHgQ4OO8tzTaLawm8vnODuwDk=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.3.0 h1:hI/7Q+DtNZ2kINb6qt/lS+IyXnHQe9e90POfeewL/ME=
+github.com/sirupsen/logrus v1.3.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
+github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/crypto v0.0.0-20180904163835-0709b304e793 h1:u+LnwYTOOW7Ukr/fppxEb1Nwz0AtPflrblfvUudpo+I=
+golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33 h1:I6FyU15t786LL7oL/hn43zqTuEGr4PN7F4XJ1p4E3Y8=
+golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
diff --git a/soap/client.go b/soap/client.go
index 49d1863..3d57261 100644
--- a/soap/client.go
+++ b/soap/client.go
@@ -27,6 +27,9 @@ func NewClient(url string) *Client {
 
 // Call performs HTTP POST request
 func (s *Client) Call(soapAction string, request, response interface{}) error {
+	if len(s.url) == 0 {
+		return errors.New("no URL to request")
+	}
 	envelope := toSendEnvelope{XMLNS: "http://www.w3.org/2003/05/soap-envelope"}
 	envelope.Header = &toSendHeader{
 		XMLNS:     "http://www.w3.org/2005/08/addressing",
diff --git a/soap/models.go b/soap/models.go
index 49d0c51..0fa6777 100644
--- a/soap/models.go
+++ b/soap/models.go
@@ -2,8 +2,6 @@ package soap
 
 import (
 	"encoding/xml"
-
-	"github.com/eduhenke/go-ocpp/messages"
 )
 
 type Envelope receivedEnvelope
@@ -75,7 +73,7 @@ type toSendHeader struct {
 	Action            string `xml:"wsa5:Action"`
 	MessageID         string `xml:"wsa5:MessageID"`
 	From              toSendFrom
-	ChargeBoxIdentity messages.ChargeBoxIdentity `xml:"urn://Ocpp/Cs/2012/06/ chargeBoxIdentity"`
+	ChargeBoxIdentity string `xml:"urn://Ocpp/Cs/2012/06/ chargeBoxIdentity"`
 }
 
 type toSendBody struct {