diff --git a/src/vector/indexeddb-worker.js b/src/vector/indexeddb-worker.ts
similarity index 100%
rename from src/vector/indexeddb-worker.js
rename to src/vector/indexeddb-worker.ts
diff --git a/src/vector/mobile_guide/index.js b/src/vector/mobile_guide/index.ts
similarity index 91%
rename from src/vector/mobile_guide/index.js
rename to src/vector/mobile_guide/index.ts
index 950ab956cba..f27d414f0a5 100644
--- a/src/vector/mobile_guide/index.js
+++ b/src/vector/mobile_guide/index.ts
@@ -1,19 +1,21 @@
 import { getVectorConfig } from '../getconfig';
 
-function onBackToElementClick() {
+function onBackToElementClick(): void {
     // Cookie should expire in 4 hours
     document.cookie = 'element_mobile_redirect_to_guide=false;path=/;max-age=14400';
     window.location.href = '../';
 }
 
 // NEVER pass user-controlled content to this function! Hardcoded strings only please.
-function renderConfigError(message) {
+function renderConfigError(message: string): void {
     const contactMsg = "If this is unexpected, please contact your system administrator " +
         "or technical support representative.";
     message = `<h2>Error loading Element</h2><p>${message}</p><p>${contactMsg}</p>`;
 
     const toHide = document.getElementsByClassName("mx_HomePage_container");
-    const errorContainers = document.getElementsByClassName("mx_HomePage_errorContainer");
+    const errorContainers = document.getElementsByClassName(
+        "mx_HomePage_errorContainer",
+    ) as HTMLCollectionOf<HTMLDialogElement>;
 
     for (const e of toHide) {
         // We have to clear the content because .style.display='none'; doesn't work
@@ -26,7 +28,7 @@ function renderConfigError(message) {
     }
 }
 
-async function initPage() {
+async function initPage(): Promise<void> {
     document.getElementById('back_to_element_button').onclick = onBackToElementClick;
 
     const config = await getVectorConfig('..');
@@ -92,7 +94,7 @@ async function initPage() {
     if (isUrl && !isUrl.endsWith('/')) isUrl += '/';
 
     if (hsUrl !== 'https://matrix.org/') {
-        document.getElementById('configure_element_button').href =
+        (document.getElementById('configure_element_button') as HTMLAnchorElement).href =
             "https://mobile.element.io?hs_url=" + encodeURIComponent(hsUrl) +
             "&is_url=" + encodeURIComponent(isUrl);
         document.getElementById('step1_heading').innerHTML= '1: Install the app';
diff --git a/webpack.config.js b/webpack.config.js
index 1bc2124f68d..9d9d0172a6e 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -55,8 +55,8 @@ module.exports = (env, argv) => {
 
         entry: {
             "bundle": "./src/vector/index.ts",
-            "indexeddb-worker": "./src/vector/indexeddb-worker.js",
-            "mobileguide": "./src/vector/mobile_guide/index.js",
+            "indexeddb-worker": "./src/vector/indexeddb-worker.ts",
+            "mobileguide": "./src/vector/mobile_guide/index.ts",
             "jitsi": "./src/vector/jitsi/index.ts",
             "usercontent": "./node_modules/matrix-react-sdk/src/usercontent/index.js",
             "recorder-worklet": "./node_modules/matrix-react-sdk/src/voice/RecorderWorklet.ts",