diff --git a/index.js b/index.js
index 840c337..0ae71f7 100644
--- a/index.js
+++ b/index.js
@@ -1349,7 +1349,7 @@ function getRecommendedSpec(idx, latitude, longitude) {
     createMcisReqVm.rootDiskType = res.data[0].rootDiskType;
 
     var diskSizeInput = diskSize.value;
-    if (isNaN(diskSizeInput)) {
+    if (isNaN(diskSizeInput) || diskSizeInput == "") {
       diskSizeInput = "default";
     }
     createMcisReqVm.rootDiskSize = diskSizeInput;
diff --git a/package.json b/package.json
index d762421..de66e73 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,7 @@
     "build": "echo 'Removing temporal cache files' && rm -rf dist/* .parcel-cache/* && mkdir -p dist/img/ && cp -r img/ dist/ && parcel build --public-url . index.html"
   },
   "description": "MapUI Client for CB-Tumblebug (display multi-cloud infra service)",
-  "version": "0.8.4",
+  "version": "0.8.5",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/cloud-barista/cb-mapui.git"