@@ -78,7 +78,7 @@ func MergeConfig(userConf, imageConf *Config) {

 			imageNat, _ := parseNat(imagePortSpec)

 			for _, userPortSpec := range userConf.PortSpecs {

 				userNat, _ := parseNat(userPortSpec)

-				if imageNat.Proto == userNat.Proto && imageNat.Frontend == userNat.Frontend {

+				if imageNat.Proto == userNat.Proto && imageNat.Backend == userNat.Backend {

 					found = true

 				}

 			}

@@ -148,7 +148,7 @@ func TestMergeConfig(t *testing.T) {

 	volumesUser["/test3"] = struct{}{}

 	configUser := &Config{

 		Dns:       []string{"3.3.3.3"},

-		PortSpecs: []string{"2222:3333", "3333:3333"},

+		PortSpecs: []string{"3333:2222", "3333:3333"},

 		Env:       []string{"VAR2=3", "VAR3=3"},

 		Volumes:   volumesUser,

 	}

@@ -165,11 +165,11 @@ func TestMergeConfig(t *testing.T) {

 	}

 	if len(configUser.PortSpecs) != 3 {

-		t.Fatalf("Expected 3 portSpecs, 1111:1111, 2222:3333 and 3333:3333, found %d", len(configUser.PortSpecs))

+		t.Fatalf("Expected 3 portSpecs, 1111:1111, 3333:2222 and 3333:3333, found %d", len(configUser.PortSpecs))

 	}

 	for _, portSpecs := range configUser.PortSpecs {

-		if portSpecs != "1111:1111" && portSpecs != "2222:3333" && portSpecs != "3333:3333" {

-			t.Fatalf("Expected 1111:1111 or 2222:3333 or 3333:3333, found %s", portSpecs)

+		if portSpecs != "1111:1111" && portSpecs != "3333:2222" && portSpecs != "3333:3333" {

+			t.Fatalf("Expected 1111:1111 or 3333:2222 or 3333:3333, found %s", portSpecs)

 		}

 	}

 	if len(configUser.Env) != 3 {