diff --git a/examples/routers/menu.vue b/examples/routers/menu.vue
index a51cdec..b2507e2 100644
--- a/examples/routers/menu.vue
+++ b/examples/routers/menu.vue
@@ -1,5 +1,5 @@
 <template>
-    <Menu active-name="1-2" :open-names="['1']">
+    <Menu active-name="1-2" :open-names="['1']" theme="dark">
         <Submenu name="1">
             <template slot="title">
                 <Icon type="ios-analytics"></Icon>
diff --git a/src/components/menu/mixin.js b/src/components/menu/mixin.js
index 6d5e29e..e234136 100644
--- a/src/components/menu/mixin.js
+++ b/src/components/menu/mixin.js
@@ -7,7 +7,7 @@ export default {
     },
     computed: {
         hasParentSubmenu () {
-            return findComponentUpward(this, 'Submenu');
+            return !!findComponentUpward(this, 'Submenu');
         },
         parentSubmenuNum () {
             return findComponentsUpward(this, 'Submenu').length;
--
libgit2 0.21.4