diff --git a/staging/src/k8s.io/legacy-cloud-providers/azure/BUILD b/staging/src/k8s.io/legacy-cloud-providers/azure/BUILD
index 8ef496f757c..409ad725022 100644
--- a/staging/src/k8s.io/legacy-cloud-providers/azure/BUILD
+++ b/staging/src/k8s.io/legacy-cloud-providers/azure/BUILD
@@ -98,6 +98,7 @@ go_test(
         "azure_storage_test.go",
         "azure_storageaccount_test.go",
         "azure_test.go",
+        "azure_utils_test.go",
         "azure_vmss_cache_test.go",
         "azure_vmss_test.go",
         "azure_wrap_test.go",
diff --git a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_controller_common.go b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_controller_common.go
index 9c466898d42..d8fc3b6798f 100644
--- a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_controller_common.go
+++ b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_controller_common.go
@@ -142,8 +142,8 @@ func (c *controllerCommon) AttachDisk(isManagedDisk bool, diskName, diskURI stri
 		return -1, fmt.Errorf("failed to get azure instance id for node %q (%v)", nodeName, err)
 	}
 
-	c.vmLockMap.LockEntry(string(nodeName))
-	defer c.vmLockMap.UnlockEntry(string(nodeName))
+	c.vmLockMap.LockEntry(strings.ToLower(string(nodeName)))
+	defer c.vmLockMap.UnlockEntry(strings.ToLower(string(nodeName)))
 
 	lun, err := c.GetNextDiskLun(nodeName)
 	if err != nil {
@@ -179,20 +179,20 @@ func (c *controllerCommon) DetachDisk(diskName, diskURI string, nodeName types.N
 	klog.V(2).Infof("detach %v from node %q", diskURI, nodeName)
 
 	// make the lock here as small as possible
-	c.vmLockMap.LockEntry(string(nodeName))
+	c.vmLockMap.LockEntry(strings.ToLower(string(nodeName)))
 	c.diskAttachDetachMap.Store(strings.ToLower(diskURI), "detaching")
 	resp, err := vmset.DetachDisk(diskName, diskURI, nodeName)
 	c.diskAttachDetachMap.Delete(strings.ToLower(diskURI))
-	c.vmLockMap.UnlockEntry(string(nodeName))
+	c.vmLockMap.UnlockEntry(strings.ToLower(string(nodeName)))
 
 	if c.cloud.CloudProviderBackoff && shouldRetryHTTPRequest(resp, err) {
 		klog.V(2).Infof("azureDisk - update backing off: detach disk(%s, %s), err: %v", diskName, diskURI, err)
 		retryErr := kwait.ExponentialBackoff(c.cloud.RequestBackoff(), func() (bool, error) {
-			c.vmLockMap.LockEntry(string(nodeName))
+			c.vmLockMap.LockEntry(strings.ToLower(string(nodeName)))
 			c.diskAttachDetachMap.Store(strings.ToLower(diskURI), "detaching")
 			resp, err := vmset.DetachDisk(diskName, diskURI, nodeName)
 			c.diskAttachDetachMap.Delete(strings.ToLower(diskURI))
-			c.vmLockMap.UnlockEntry(string(nodeName))
+			c.vmLockMap.UnlockEntry(strings.ToLower(string(nodeName)))
 			return c.cloud.processHTTPRetryResponse(nil, "", resp, err)
 		})
 		if retryErr != nil {
diff --git a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_utils.go b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_utils.go
index bef369c83cb..d4b5aba8015 100644
--- a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_utils.go
+++ b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_utils.go
@@ -1,7 +1,7 @@
 // +build !providerless
 
 /*
-Copyright 2018 The Kubernetes Authors.
+Copyright 2019 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.
diff --git a/staging/src/k8s.io/legacy-cloud-providers/azure/azure_utils_test.go b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_utils_test.go
new file mode 100644
index 00000000000..cb527f37dd2
--- /dev/null
+++ b/staging/src/k8s.io/legacy-cloud-providers/azure/azure_utils_test.go
@@ -0,0 +1,85 @@
+// +build !providerless
+
+/*
+Copyright 2019 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"
+	"time"
+)
+
+func TestSimpleLockEntry(t *testing.T) {
+	testLockMap := newLockMap()
+
+	callbackChan1 := make(chan interface{})
+	go testLockMap.lockAndCallback(t, "entry1", callbackChan1)
+	ensureCallbackHappens(t, callbackChan1)
+}
+
+func TestSimpleLockUnlockEntry(t *testing.T) {
+	testLockMap := newLockMap()
+
+	callbackChan1 := make(chan interface{})
+	go testLockMap.lockAndCallback(t, "entry1", callbackChan1)
+	ensureCallbackHappens(t, callbackChan1)
+	testLockMap.UnlockEntry("entry1")
+}
+
+func TestConcurrentLockEntry(t *testing.T) {
+	testLockMap := newLockMap()
+
+	callbackChan1 := make(chan interface{})
+	callbackChan2 := make(chan interface{})
+
+	go testLockMap.lockAndCallback(t, "entry1", callbackChan1)
+	ensureCallbackHappens(t, callbackChan1)
+
+	go testLockMap.lockAndCallback(t, "entry1", callbackChan2)
+	ensureNoCallback(t, callbackChan2)
+
+	testLockMap.UnlockEntry("entry1")
+	ensureCallbackHappens(t, callbackChan2)
+	testLockMap.UnlockEntry("entry1")
+}
+
+func (lm *lockMap) lockAndCallback(t *testing.T, entry string, callbackChan chan<- interface{}) {
+	lm.LockEntry(entry)
+	callbackChan <- true
+}
+
+var callbackTimeout = 2 * time.Second
+
+func ensureCallbackHappens(t *testing.T, callbackChan <-chan interface{}) bool {
+	select {
+	case <-callbackChan:
+		return true
+	case <-time.After(callbackTimeout):
+		t.Fatalf("timed out waiting for callback")
+		return false
+	}
+}
+
+func ensureNoCallback(t *testing.T, callbackChan <-chan interface{}) bool {
+	select {
+	case <-callbackChan:
+		t.Fatalf("unexpected callback")
+		return false
+	case <-time.After(callbackTimeout):
+		return true
+	}
+}