diff --git a/json-box.vue b/json-box.vue
index 7fa6ad3..7a95910 100644
--- a/json-box.vue
+++ b/json-box.vue
@@ -35,7 +35,7 @@ export default {
     },
     computed: {
         valueType() {
-            if (this.value === null) {
+            if (this.value === null || this.value === undefined) {
                 return 'Null';
             } else if (Array.isArray(this.value)) {
                 return 'Array';
diff --git a/types/json-null.vue b/types/json-null.vue
index 7e5768f..b424821 100644
--- a/types/json-null.vue
+++ b/types/json-null.vue
@@ -1,5 +1,5 @@
 <template>
-    <span class="json-null">null</span>
+    <span class="json-null">{{ jsonValue === null ? 'null' : 'undefined' }}</span>
 </template>
 
 <script>