diff --git a/pkg/cloudprovider/providers/azure/BUILD b/pkg/cloudprovider/providers/azure/BUILD
index acd41bdd717..cd4f0a67db0 100644
--- a/pkg/cloudprovider/providers/azure/BUILD
+++ b/pkg/cloudprovider/providers/azure/BUILD
@@ -23,6 +23,7 @@ go_library(
         "azure_storage.go",
         "azure_storageaccount.go",
         "azure_util.go",
+        "azure_util_vmss.go",
         "azure_wrap.go",
         "azure_zones.go",
     ],
@@ -57,7 +58,10 @@ go_library(
 
 go_test(
     name = "go_default_test",
-    srcs = ["azure_test.go"],
+    srcs = [
+        "azure_test.go",
+        "azure_util_test.go",
+    ],
     importpath = "k8s.io/kubernetes/pkg/cloudprovider/providers/azure",
     library = ":go_default_library",
     deps = [
@@ -66,6 +70,7 @@ go_test(
         "//vendor/github.com/Azure/azure-sdk-for-go/arm/compute:go_default_library",
         "//vendor/github.com/Azure/azure-sdk-for-go/arm/network:go_default_library",
         "//vendor/github.com/Azure/go-autorest/autorest/to:go_default_library",
+        "//vendor/github.com/stretchr/testify/assert:go_default_library",
         "//vendor/k8s.io/api/core/v1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/types:go_default_library",
diff --git a/pkg/cloudprovider/providers/azure/azure_fakes.go b/pkg/cloudprovider/providers/azure/azure_fakes.go
index 98f35b1c572..1bc0d0c811d 100644
--- a/pkg/cloudprovider/providers/azure/azure_fakes.go
+++ b/pkg/cloudprovider/providers/azure/azure_fakes.go
@@ -339,6 +339,10 @@ func (fIC fakeAzureInterfacesClient) Get(resourceGroupName string, networkInterf
 	}
 }
 
+func (fIC fakeAzureInterfacesClient) GetVirtualMachineScaleSetNetworkInterface(resourceGroupName string, virtualMachineScaleSetName string, virtualmachineIndex string, networkInterfaceName string, expand string) (result network.Interface, err error) {
+	return result, nil
+}
+
 type fakeAzureVirtualMachinesClient struct {
 	mutex     *sync.Mutex
 	FakeStore map[string]map[string]compute.VirtualMachine
diff --git a/pkg/cloudprovider/providers/azure/azure_util_test.go b/pkg/cloudprovider/providers/azure/azure_util_test.go
new file mode 100644
index 00000000000..46f351f47b5
--- /dev/null
+++ b/pkg/cloudprovider/providers/azure/azure_util_test.go
@@ -0,0 +1,53 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package azure
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetVmssInstanceID(t *testing.T) {
+	tests := []struct {
+		msg                string
+		machineName        string
+		expectError        bool
+		expectedInstanceID string
+	}{{
+		msg:         "invalid vmss instance name",
+		machineName: "vmvm",
+		expectError: true,
+	},
+		{
+			msg:                "valid vmss instance name",
+			machineName:        "vm00000Z",
+			expectError:        false,
+			expectedInstanceID: "35",
+		},
+	}
+
+	for i, test := range tests {
+		instanceID, err := getVmssInstanceID(test.machineName)
+		if test.expectError {
+			assert.Error(t, err, fmt.Sprintf("TestCase[%d]: %s", i, test.msg))
+		} else {
+			assert.Equal(t, test.expectedInstanceID, instanceID, fmt.Sprintf("TestCase[%d]: %s", i, test.msg))
+		}
+	}
+}