diff --git a/background.js b/background.js
index b051d5c9..5d528d22 100644
--- a/background.js
+++ b/background.js
@@ -70,11 +70,11 @@ chrome.runtime.onInstalled.addListener(() => {
 
   chrome.storage.local.get(["index", "font", "size", "mode", "focus"], local => {
     chrome.storage.local.set({
-      index: (local.index !== "undefined" ? local.index : defaultIndex),
+      index: (typeof local.index !== "undefined" ? local.index : defaultIndex),
       font: (local.font || defaultFont),
       size: (local.size || defaultSize),
       mode: (local.mode || defaultMode),
-      focus: (local.focus !== "undefined" ? local.focus : defaultFocus),
+      focus: (typeof local.focus !== "undefined" ? local.focus : defaultFocus),
     });
   });