diff --git a/src/libs/UnreadIndicatorUpdater/index.js b/src/libs/UnreadIndicatorUpdater/index.ts
similarity index 60%
rename from src/libs/UnreadIndicatorUpdater/index.js
rename to src/libs/UnreadIndicatorUpdater/index.ts
index ee686444abfd..da45057bc46d 100644
--- a/src/libs/UnreadIndicatorUpdater/index.js
+++ b/src/libs/UnreadIndicatorUpdater/index.ts
@@ -1,18 +1,20 @@
-import Onyx from 'react-native-onyx';
-import _ from 'underscore';
+import Onyx, {OnyxCollection} from 'react-native-onyx';
 import * as ReportUtils from '@libs/ReportUtils';
 import Navigation, {navigationRef} from '@navigation/Navigation';
 import ONYXKEYS from '@src/ONYXKEYS';
-import updateUnread from './updateUnread/index';
+import {Report} from '@src/types/onyx';
+import updateUnread from './updateUnread';
 
-let allReports = [];
+let allReports: OnyxCollection<Report> = {};
 
 const triggerUnreadUpdate = () => {
     const currentReportID = navigationRef.isReady() ? Navigation.getTopmostReportId() : '';
 
     // We want to keep notification count consistent with what can be accessed from the LHN list
-    const unreadReports = _.filter(allReports, (report) => ReportUtils.isUnread(report) && ReportUtils.shouldReportBeInOptionList(report, currentReportID));
-    updateUnread(_.size(unreadReports));
+    const unreadReports = Object.values(allReports ?? {}).filter(
+        (report) => ReportUtils.isUnread(report) && ReportUtils.shouldReportBeInOptionList(report, currentReportID ?? '', false, [], {}),
+    );
+    updateUnread(unreadReports.length);
 };
 
 Onyx.connect({
diff --git a/src/libs/UnreadIndicatorUpdater/updateUnread/index.android.js b/src/libs/UnreadIndicatorUpdater/updateUnread/index.android.js
deleted file mode 100644
index 731b8058a9a7..000000000000
--- a/src/libs/UnreadIndicatorUpdater/updateUnread/index.android.js
+++ /dev/null
@@ -1,2 +0,0 @@
-// Android does not yet implement this
-export default () => {};
diff --git a/src/libs/UnreadIndicatorUpdater/updateUnread/index.android.ts b/src/libs/UnreadIndicatorUpdater/updateUnread/index.android.ts
new file mode 100644
index 000000000000..bd7b2cbc4752
--- /dev/null
+++ b/src/libs/UnreadIndicatorUpdater/updateUnread/index.android.ts
@@ -0,0 +1,6 @@
+import UpdateUnread from './types';
+
+// Android does not yet implement this
+const updateUnread: UpdateUnread = () => {};
+
+export default updateUnread;
diff --git a/src/libs/UnreadIndicatorUpdater/updateUnread/index.desktop.js b/src/libs/UnreadIndicatorUpdater/updateUnread/index.desktop.ts
similarity index 77%
rename from src/libs/UnreadIndicatorUpdater/updateUnread/index.desktop.js
rename to src/libs/UnreadIndicatorUpdater/updateUnread/index.desktop.ts
index b9a689e89c42..e5d2fca43bf4 100644
--- a/src/libs/UnreadIndicatorUpdater/updateUnread/index.desktop.js
+++ b/src/libs/UnreadIndicatorUpdater/updateUnread/index.desktop.ts
@@ -1,14 +1,14 @@
 import ELECTRON_EVENTS from '../../../../desktop/ELECTRON_EVENTS';
+import UpdateUnread from './types';
 
 /**
  * Set the badge on desktop
  *
- * @param {Number} totalCount
  */
-function updateUnread(totalCount) {
+const updateUnread: UpdateUnread = (totalCount) => {
     // Ask the main Electron process to update our
     // badge count in the Mac OS dock icon
     window.electron.send(ELECTRON_EVENTS.REQUEST_UPDATE_BADGE_COUNT, totalCount);
-}
+};
 
 export default updateUnread;
diff --git a/src/libs/UnreadIndicatorUpdater/updateUnread/index.ios.js b/src/libs/UnreadIndicatorUpdater/updateUnread/index.ios.ts
similarity index 69%
rename from src/libs/UnreadIndicatorUpdater/updateUnread/index.ios.js
rename to src/libs/UnreadIndicatorUpdater/updateUnread/index.ios.ts
index 62ee00828566..d6fac7c7771d 100644
--- a/src/libs/UnreadIndicatorUpdater/updateUnread/index.ios.js
+++ b/src/libs/UnreadIndicatorUpdater/updateUnread/index.ios.ts
@@ -1,13 +1,12 @@
 import Airship from '@ua/react-native-airship';
+import UpdateUnread from './types';
 
 /**
  * Set the App Icon badge with the number of
  * unread messages on iOS
- *
- * @param {Number} totalCount
  */
-function updateUnread(totalCount) {
+const updateUnread: UpdateUnread = (totalCount) => {
     Airship.push.iOS.setBadgeNumber(totalCount);
-}
+};
 
 export default updateUnread;
diff --git a/src/libs/UnreadIndicatorUpdater/updateUnread/index.website.js b/src/libs/UnreadIndicatorUpdater/updateUnread/index.ts
similarity index 76%
rename from src/libs/UnreadIndicatorUpdater/updateUnread/index.website.js
rename to src/libs/UnreadIndicatorUpdater/updateUnread/index.ts
index 56aa7f02509d..46015f4e5e03 100644
--- a/src/libs/UnreadIndicatorUpdater/updateUnread/index.website.js
+++ b/src/libs/UnreadIndicatorUpdater/updateUnread/index.ts
@@ -2,14 +2,13 @@
  * Web browsers have a tab title and favicon which can be updated to show there are unread comments
  */
 import CONFIG from '@src/CONFIG';
+import UpdateUnread from './types';
 
 let unreadTotalCount = 0;
 /**
  * Set the page title on web
- *
- * @param {Number} totalCount
  */
-function updateUnread(totalCount) {
+const updateUnread: UpdateUnread = (totalCount) => {
     const hasUnread = totalCount !== 0;
     unreadTotalCount = totalCount;
     // This setTimeout is required because due to how react rendering messes with the DOM, the document title can't be modified synchronously, and we must wait until all JS is done
@@ -19,9 +18,12 @@ function updateUnread(totalCount) {
         // seems to improve this issue.
         document.title = '';
         document.title = hasUnread ? `(${totalCount}) ${CONFIG.SITE_TITLE}` : CONFIG.SITE_TITLE;
-        document.getElementById('favicon').href = hasUnread ? CONFIG.FAVICON.UNREAD : CONFIG.FAVICON.DEFAULT;
+        const favicon = document.getElementById('favicon');
+        if (favicon instanceof HTMLLinkElement) {
+            favicon.href = hasUnread ? CONFIG.FAVICON.UNREAD : CONFIG.FAVICON.DEFAULT;
+        }
     }, 0);
-}
+};
 
 window.addEventListener('popstate', () => {
     updateUnread(unreadTotalCount);
diff --git a/src/libs/UnreadIndicatorUpdater/updateUnread/types.ts b/src/libs/UnreadIndicatorUpdater/updateUnread/types.ts
new file mode 100644
index 000000000000..afbb2741a454
--- /dev/null
+++ b/src/libs/UnreadIndicatorUpdater/updateUnread/types.ts
@@ -0,0 +1,3 @@
+type UpdateUnread = (totalCount: number) => void;
+
+export default UpdateUnread;