diff --git a/src/components/layout/top-bar.vue b/src/components/layout/top-bar.vue
index f8af218..74ee561 100644
--- a/src/components/layout/top-bar.vue
+++ b/src/components/layout/top-bar.vue
@@ -90,7 +90,7 @@ export default {
     }
   },
   created() {
-    this.$vuetify.theme.dark = getCache('theme_dark')
+    this.$vuetify.theme.dark = getCache('theme_dark', true)
   },
   methods: {
     handleLogout() {
diff --git a/src/utils/cache.js b/src/utils/cache.js
index 04cb478..cf5e0df 100644
--- a/src/utils/cache.js
+++ b/src/utils/cache.js
@@ -6,12 +6,12 @@ export function setCache(k, v) {
   window.localStorage.setItem(k, content)
 }
 
-export function getCache(k) {
+export function getCache(k, defaultValue) {
   const content = window.localStorage.getItem(k)
   try {
     const obj = JSON.parse(content)
     return obj.value
   } catch (e) {
-    return content
+    return defaultValue === undefined ? content : defaultValue
   }
 }