diff --git a/pkg/cloudprovider/providers/azure/BUILD b/pkg/cloudprovider/providers/azure/BUILD
index 2fd8479284a..9587610ef8e 100644
--- a/pkg/cloudprovider/providers/azure/BUILD
+++ b/pkg/cloudprovider/providers/azure/BUILD
@@ -75,6 +75,7 @@ go_test(
         "azure_storage_test.go",
         "azure_storageaccount_test.go",
         "azure_test.go",
+        "azure_vmss_cache_test.go",
         "azure_vmss_test.go",
         "azure_wrap_test.go",
     ],
diff --git a/pkg/cloudprovider/providers/azure/azure_vmss_cache.go b/pkg/cloudprovider/providers/azure/azure_vmss_cache.go
index 47b0695f422..c6683f460db 100644
--- a/pkg/cloudprovider/providers/azure/azure_vmss_cache.go
+++ b/pkg/cloudprovider/providers/azure/azure_vmss_cache.go
@@ -27,6 +27,8 @@ import (
 )
 
 var (
+	vmssNameSeparator = "_"
+
 	nodeNameToScaleSetMappingKey = "k8sNodeNameToScaleSetMappingKey"
 	availabilitySetNodesKey      = "k8sAvailabilitySetNodesKey"
 
@@ -41,11 +43,11 @@ var (
 type nodeNameToScaleSetMapping map[string]string
 
 func (ss *scaleSet) makeVmssVMName(scaleSetName, instanceID string) string {
-	return fmt.Sprintf("%s_%s", scaleSetName, instanceID)
+	return fmt.Sprintf("%s%s%s", scaleSetName, vmssNameSeparator, instanceID)
 }
 
 func (ss *scaleSet) extractVmssVMName(name string) (string, string, error) {
-	ret := strings.Split(name, "_")
+	ret := strings.Split(name, vmssNameSeparator)
 	if len(ret) != 2 {
 		glog.Errorf("Failed to extract vmssVMName %q", name)
 		return "", "", ErrorNotVmssInstance
@@ -88,7 +90,7 @@ func (ss *scaleSet) newNodeNameToScaleSetMappingCache() (*timedCache, error) {
 
 			for _, vm := range vms {
 				if vm.OsProfile == nil || vm.OsProfile.ComputerName == nil {
-					glog.Warningf("failed to get computerName for vmssVM (%q)", *vm.Name)
+					glog.Warningf("failed to get computerName for vmssVM (%q)", vm.Name)
 					continue
 				}
 
diff --git a/pkg/cloudprovider/providers/azure/azure_vmss_cache_test.go b/pkg/cloudprovider/providers/azure/azure_vmss_cache_test.go
new file mode 100644
index 00000000000..284a26d340d
--- /dev/null
+++ b/pkg/cloudprovider/providers/azure/azure_vmss_cache_test.go
@@ -0,0 +1,62 @@
+/*
+Copyright 2018 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 (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestExtractVmssVMName(t *testing.T) {
+	ss := &scaleSet{}
+	cases := []struct {
+		description        string
+		vmName             string
+		expectError        bool
+		expectedScaleSet   string
+		expectedInstanceID string
+	}{
+		{
+			description: "wrong vmss VM name should report error",
+			vmName:      "vm1234",
+			expectError: true,
+		},
+		{
+			description: "wrong VM name separator should report error",
+			vmName:      "vm-1234",
+			expectError: true,
+		},
+		{
+			description:        "correct vmss VM name should return correct scaleSet and instanceID",
+			vmName:             "vm_1234",
+			expectedScaleSet:   "vm",
+			expectedInstanceID: "1234",
+		},
+	}
+
+	for _, c := range cases {
+		ssName, instanceID, err := ss.extractVmssVMName(c.vmName)
+		if c.expectError {
+			assert.Error(t, err, c.description)
+			continue
+		}
+
+		assert.Equal(t, c.expectedScaleSet, ssName, c.description)
+		assert.Equal(t, c.expectedInstanceID, instanceID, c.description)
+	}
+}