diff --git a/cluster-autoscaler/cloudprovider/azure/azure_scale_set.go b/cluster-autoscaler/cloudprovider/azure/azure_scale_set.go
index d746d4e0ad3..405b38bda98 100644
--- a/cluster-autoscaler/cloudprovider/azure/azure_scale_set.go
+++ b/cluster-autoscaler/cloudprovider/azure/azure_scale_set.go
@@ -215,12 +215,14 @@ func (scaleSet *ScaleSet) updateVMSSCapacity(size int64) {
 	var isSuccess bool
 	var err error
 
+	scaleSet.sizeMutex.Lock()
+	defer scaleSet.sizeMutex.Unlock()
+
 	defer func() {
 		if err != nil {
 			klog.Errorf("Failed to update the capacity for vmss %s with error %v, invalidate the cache so as to get the real size from API", scaleSet.Name, err)
 			// Invalidate the VMSS size cache in order to fetch the size from the API.
-			scaleSet.sizeMutex.Lock()
-			defer scaleSet.sizeMutex.Unlock()
+
 			scaleSet.lastSizeRefresh = time.Now().Add(-1 * vmssSizeRefreshPeriod)
 		}
 	}()