diff --git a/src/panel.js b/src/panel.js
index abb186ff..159b35b3 100644
--- a/src/panel.js
+++ b/src/panel.js
@@ -141,7 +141,7 @@ const isSiteInContainer = async(panelId) => {
 
   const activeRootDomain = await getActiveRootDomainFromBackground();
 
-  if (addedSitesList.includes(activeRootDomain)) {
+  if (addedSitesList && addedSitesList.includes(activeRootDomain)) {
     return true;
   }
 };
@@ -345,7 +345,7 @@ document.addEventListener("DOMContentLoaded", async () => {
   const storage = await browser.storage.local.get();
   const currentPanel = storage.CURRENT_PANEL;
 
-  const onboarding = (currentPanel.includes("onboarding"));
+  const onboarding = (currentPanel && currentPanel.includes("onboarding"));
   if (!onboarding) {
     return buildPanel(currentPanel);
   }
diff --git a/test/features/add-domain-to-fbc.test.js b/test/features/add-domain-to-fbc.test.js
index e8d59de1..4dd2fd97 100644
--- a/test/features/add-domain-to-fbc.test.js
+++ b/test/features/add-domain-to-fbc.test.js
@@ -31,6 +31,8 @@ describe("Add domain to Facebook Container", () => {
           removeDomain: "example.com"
         });
 
+        await sleep();
+
         const [promise] = await background.browser.runtime.onMessage.addListener.yield({message: "what-sites-are-added"});
         const sites = await promise;
         expect(sites.includes("example.com")).to.be.false;
@@ -39,3 +41,7 @@ describe("Add domain to Facebook Container", () => {
   });
 
 });
+
+async function sleep(ms = 100) {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}