diff --git a/background.js b/background.js
index f96d376..a0c42ff 100644
--- a/background.js
+++ b/background.js
@@ -1,6 +1,8 @@
 const browserTypeFirefox = 1;
 const browserTypeChrome = 2;
 
+const storageTabCountKey = 'tab-count';
+
 const getBrowser = () => {
     try {
         return [browser, browserTypeFirefox];
@@ -13,14 +15,34 @@ const maxNumTabs = 10;
 const [browser, browserType] = getBrowser();
 
 browser.tabs.onCreated.addListener(newTab => {
-    getTabs().then(tabs => {
-        const numTabsOpen = tabs.filter(tab => !tab.pinned).length;
-        if (numTabsOpen > maxNumTabs) {
+    getUnpinnedTabs().then(tabs => {
+        browser.storage.local.set({[storageTabCountKey]: tabs.length});
+        if (tabs.length > maxNumTabs) {
             browser.tabs.remove(newTab.id);
         }
     });
 });
 
+browser.tabs.onRemoved.addListener(tabId => {
+    // This listener can get fired before the tab is removed, so we'll need
+    // to explicitly filter out the removed tab.
+    getUnpinnedTabs()
+        .then(tabs => tabs.filter(tab => tab.id !== tabId))
+        .then(tabs => {
+            browser.storage.local.set({[storageTabCountKey]: tabs.length});
+        });
+})
+
+browser.storage.onChanged.addListener(changes => {
+    if (changes.hasOwnProperty(storageTabCountKey)) {
+        browser.storage.local.get(storageTabCountKey, items => {
+            browser.browserAction.setBadgeText({
+                text: items[storageTabCountKey].toString()
+            });
+        });
+    }
+});
+
 const getTabs = () => {
     if (browserType === browserTypeChrome) {
         return new Promise((resolve, reject) => {
diff --git a/manifest.json b/manifest.json
index 9a786cc..000d37b 100644
--- a/manifest.json
+++ b/manifest.json
@@ -8,7 +8,8 @@
         "96": "icons/icon96.png"
     },
     "permissions": [
-        "tabs"
+        "tabs",
+        "storage"
     ],
     "background": {
         "scripts": ["background.js"]