diff --git a/build-scripts/webpack.js b/build-scripts/webpack.js
index fa9bfb9edd..d95cc350dc 100644
--- a/build-scripts/webpack.js
+++ b/build-scripts/webpack.js
@@ -118,7 +118,24 @@ const createAppConfig = ({ isProdBuild, latestBuild, isStatsBuild }) => {
     devtool: genDevTool(isProdBuild),
     entry,
     module: {
-      rules: [babelLoaderConfig({ latestBuild }), cssLoader, htmlLoader],
+      rules: [
+        {
+          test: /\.ts|tsx$/,
+          exclude: /node_modules/,
+          use: [
+            {
+              loader: "ts-loader",
+              options: {
+                compilerOptions: latestBuild
+                  ? { noEmit: false }
+                  : { target: "es5", noEmit: false },
+              },
+            },
+          ],
+        },
+        cssLoader,
+        htmlLoader,
+      ],
     },
     optimization: optimization(latestBuild),
     plugins: [
diff --git a/package.json b/package.json
index d7490e5ff1..64911a81f7 100644
--- a/package.json
+++ b/package.json
@@ -161,6 +161,7 @@
     "require-dir": "^1.2.0",
     "sinon": "^7.3.1",
     "terser-webpack-plugin": "^1.2.3",
+    "ts-loader": "^6.0.4",
     "ts-mocha": "^6.0.0",
     "tslint": "^5.14.0",
     "tslint-config-prettier": "^1.18.0",
diff --git a/src/layouts/home-assistant.ts b/src/layouts/home-assistant.ts
index 09c762e675..551a45a999 100644
--- a/src/layouts/home-assistant.ts
+++ b/src/layouts/home-assistant.ts
@@ -14,7 +14,7 @@ import { HassElement } from "../state/hass-element";
 
 export class HomeAssistantAppEl extends HassElement {
   @property() private _route?: Route;
-  @property() private _error?: boolean;
+  @property() private _error = false;
   @property() private _panelUrl?: string;
 
   protected render() {
@@ -49,6 +49,7 @@ export class HomeAssistantAppEl extends HassElement {
   }
 
   protected updated(changedProps: PropertyValues): void {
+    super.updated(changedProps);
     if (changedProps.has("_panelUrl")) {
       this.panelUrlChanged(this._panelUrl!);
       this._updateHass({ panelUrl: this._panelUrl });
@@ -70,7 +71,11 @@ export class HomeAssistantAppEl extends HassElement {
     }
   }
 
-  private _routeChanged(ev) {
+  private async _routeChanged(ev) {
+    // routeChangged event listener is called while we're doing the fist render,
+    // causing the update to be ignored. So delay it to next task (Lit render is sync).
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
     const route = ev.detail.value as Route;
     // If it's the first route that we process,
     // check if we should navigate away from /
diff --git a/src/panels/custom/ha-panel-custom.ts b/src/panels/custom/ha-panel-custom.ts
index 563ccb6a18..1703e1e9fa 100644
--- a/src/panels/custom/ha-panel-custom.ts
+++ b/src/panels/custom/ha-panel-custom.ts
@@ -52,6 +52,7 @@ export class HaPanelCustom extends UpdatingElement {
       return;
     }
     const props = {};
+    // @ts-ignore
     for (const key of changedProps.keys()) {
       props[key] = this[key];
     }
diff --git a/src/panels/lovelace/cards/hui-picture-elements-card.ts b/src/panels/lovelace/cards/hui-picture-elements-card.ts
index 13157273a5..6d6a07e501 100644
--- a/src/panels/lovelace/cards/hui-picture-elements-card.ts
+++ b/src/panels/lovelace/cards/hui-picture-elements-card.ts
@@ -22,7 +22,9 @@ class HuiPictureElementsCard extends LitElement implements LovelaceCard {
 
   set hass(hass: HomeAssistant) {
     this._hass = hass;
-    for (const el of this.shadowRoot!.querySelectorAll("#root > *")) {
+    for (const el of Array.from(
+      this.shadowRoot!.querySelectorAll("#root > *")
+    )) {
       const element = el as LovelaceElement;
       element.hass = this._hass;
     }
diff --git a/src/resources/jquery.roundslider.ondemand.ts b/src/resources/jquery.roundslider.ondemand.ts
index 3c92056f97..487b367f8b 100644
--- a/src/resources/jquery.roundslider.ondemand.ts
+++ b/src/resources/jquery.roundslider.ondemand.ts
@@ -1,13 +1,13 @@
 import { TemplateResult } from "lit-element";
 
-type LoadedRoundSlider = Promise<{
+interface LoadedRoundSlider {
   roundSliderStyle: TemplateResult;
   jQuery: any;
-}>;
+}
 
-let loaded: LoadedRoundSlider;
+let loaded: Promise<LoadedRoundSlider>;
 
-export const loadRoundslider = async (): LoadedRoundSlider => {
+export const loadRoundslider = async (): Promise<LoadedRoundSlider> => {
   if (!loaded) {
     loaded = import(/* webpackChunkName: "jquery-roundslider" */ "./jquery.roundslider");
   }
diff --git a/src/state/hass-base-mixin.ts b/src/state/hass-base-mixin.ts
index f41d6752d2..df5d9e7352 100644
--- a/src/state/hass-base-mixin.ts
+++ b/src/state/hass-base-mixin.ts
@@ -2,6 +2,7 @@ import {
   Constructor,
   // @ts-ignore
   property,
+  PropertyDeclarations,
 } from "lit-element";
 import { Auth, Connection } from "home-assistant-js-websocket";
 import { HomeAssistant } from "../types";
@@ -26,8 +27,15 @@ export default <T>(superClass: Constructor<T>): Constructor<T & HassBaseEl> =>
   class extends superClass {
     protected _pendingHass: Partial<HomeAssistant> = {};
     private __provideHass: HTMLElement[] = [];
-    // @ts-ignore
-    @property() protected hass: HomeAssistant;
+
+    // Decorators not possible in anonymous classes
+    static get properties(): PropertyDeclarations {
+      return {
+        hass: {},
+      };
+    }
+
+    protected hass!: HomeAssistant;
 
     // Exists so all methods can safely call super method
     protected hassConnected() {
diff --git a/tsconfig.json b/tsconfig.json
index 7ca6093963..6e9415d1ab 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -12,6 +12,7 @@
     "noImplicitReturns": true,
     "noFallthroughCasesInSwitch": true,
     "strict": true,
+    "sourceMap": true,
     "noImplicitAny": false,
     "skipLibCheck": true,
     "resolveJsonModule": true,
diff --git a/yarn.lock b/yarn.lock
index be74dac0f2..98d2074780 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3653,6 +3653,13 @@ braces@^2.3.1, braces@^2.3.2:
     split-string "^3.0.2"
     to-regex "^3.0.1"
 
+braces@^3.0.1:
+  version "3.0.2"
+  resolved "https://registry.yarnpkg.com/braces/-/braces-3.0.2.tgz#3454e1a462ee8d599e236df336cd9ea4f8afe107"
+  integrity sha512-b8um+L1RzM3WDSzvhm6gIz1yfTbBt6YTlcEKAvsmqCZZFw46z626lVj9j1yEPW33H5H+lBQpZMP1k8l+78Ha0A==
+  dependencies:
+    fill-range "^7.0.1"
+
 brorand@^1.0.1:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/brorand/-/brorand-1.1.0.tgz#12c25efe40a45e3c323eb8675a0a0ce57b22371f"
@@ -5518,7 +5525,7 @@ engine.io@~3.3.1:
     engine.io-parser "~2.1.0"
     ws "~6.1.0"
 
-enhanced-resolve@^4.1.0:
+enhanced-resolve@^4.0.0, enhanced-resolve@^4.1.0:
   version "4.1.0"
   resolved "https://registry.yarnpkg.com/enhanced-resolve/-/enhanced-resolve-4.1.0.tgz#41c7e0bfdfe74ac1ffe1e57ad6a5c6c9f3742a7f"
   integrity sha512-F/7vkyTtyc/llOIn8oWclcB25KdRaiPBpZYDgJHgh/UHtpgT2p2eldQgtQnLtUvfMKPKxbRaQM/hHkvLHt1Vng==
@@ -6287,6 +6294,13 @@ fill-range@^4.0.0:
     repeat-string "^1.6.1"
     to-regex-range "^2.1.0"
 
+fill-range@^7.0.1:
+  version "7.0.1"
+  resolved "https://registry.yarnpkg.com/fill-range/-/fill-range-7.0.1.tgz#1919a6a7c75fe38b2c7c77e5198535da9acdda40"
+  integrity sha512-qOo9F+dMUmC2Lcb4BbVvnKJxTPjCm+RRpe4gDuGrzkL7mEVl/djYSu2OdQ2Pa302N4oqkSg9ir6jaLWJ2USVpQ==
+  dependencies:
+    to-regex-range "^5.0.1"
+
 filled-array@^1.0.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/filled-array/-/filled-array-1.1.0.tgz#c3c4f6c663b923459a9aa29912d2d031f1507f84"
@@ -8070,6 +8084,11 @@ is-number@^4.0.0:
   resolved "https://registry.yarnpkg.com/is-number/-/is-number-4.0.0.tgz#0026e37f5454d73e356dfe6564699867c6a7f0ff"
   integrity sha512-rSklcAIlf1OmFdyAqbnWTLVelsQ58uvZ66S/ZyawjWqIviTWCjg2PzVGw8WUA+nNuPTqb4wgA+NszrJ+08LlgQ==
 
+is-number@^7.0.0:
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/is-number/-/is-number-7.0.0.tgz#7535345b896734d5f80c4d06c50955527a14f12b"
+  integrity sha512-41Cifkg6e8TylSpdtTpeLVMqvSBEVzTttHvERD741+pnZ8ANv0004MRL43QKPDlK9cGvNp6NZWZUBlbGXYxxng==
+
 is-obj@^1.0.0, is-obj@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/is-obj/-/is-obj-1.0.1.tgz#3e4729ac1f5fde025cd7d83a896dab9f4f67db0f"
@@ -9504,6 +9523,14 @@ micromatch@^3.0.4, micromatch@^3.1.10, micromatch@^3.1.4, micromatch@^3.1.8:
     snapdragon "^0.8.1"
     to-regex "^3.0.2"
 
+micromatch@^4.0.0:
+  version "4.0.2"
+  resolved "https://registry.yarnpkg.com/micromatch/-/micromatch-4.0.2.tgz#4fcb0999bf9fbc2fcbdd212f6d629b9a56c39259"
+  integrity sha512-y7FpHSbMUMoyPbYUSzO6PaZ6FyRnQOpHuKwbo1G+Knck95XVU4QAiKdGEnj5wwoS7PlOgthX/09u5iFJ+aYf5Q==
+  dependencies:
+    braces "^3.0.1"
+    picomatch "^2.0.5"
+
 miller-rabin@^4.0.0:
   version "4.0.1"
   resolved "https://registry.yarnpkg.com/miller-rabin/-/miller-rabin-4.0.1.tgz#f080351c865b0dc562a8462966daa53543c78a4d"
@@ -10689,6 +10716,11 @@ performance-now@^2.1.0:
   resolved "https://registry.yarnpkg.com/performance-now/-/performance-now-2.1.0.tgz#6309f4e0e5fa913ec1c69307ae364b4b377c9e7b"
   integrity sha1-Ywn04OX6kT7BxpMHrjZLSzd8nns=
 
+picomatch@^2.0.5:
+  version "2.0.7"
+  resolved "https://registry.yarnpkg.com/picomatch/-/picomatch-2.0.7.tgz#514169d8c7cd0bdbeecc8a2609e34a7163de69f6"
+  integrity sha512-oLHIdio3tZ0qH76NybpeneBhYVj0QFTfXEFTc/B3zKQspYfYYkWYgFsmzo+4kvId/bQRcNkVeguI3y+CD22BtA==
+
 pify@^2.0.0, pify@^2.3.0:
   version "2.3.0"
   resolved "https://registry.yarnpkg.com/pify/-/pify-2.3.0.tgz#ed141a6ac043a849ea588498e7dca8b15330e90c"
@@ -12075,7 +12107,7 @@ semver-greatest-satisfied-range@^1.1.0:
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.7.0.tgz#790a7cf6fea5459bac96110b29b60412dc8ff96b"
   integrity sha512-Ya52jSX2u7QKghxeoFGpLwCtGlt7j0oY9DYb5apt9nPlJ42ID+ulTXESnt/qAQcoSERyZ5sl3LDIOw0nAn/5DA==
 
-semver@^6.1.2:
+semver@^6.0.0, semver@^6.1.2:
   version "6.3.0"
   resolved "https://registry.yarnpkg.com/semver/-/semver-6.3.0.tgz#ee0a64c8af5e8ceea67687b133761e1becbd1d3d"
   integrity sha512-b39TBaTSfV6yBrapU89p5fKekE2m/NwnDocOVruQFS1/veMgdzuPcnOM34M6CwxW8jH/lxEa5rBoDeUwu5HHTw==
@@ -13257,6 +13289,13 @@ to-regex-range@^2.1.0:
     is-number "^3.0.0"
     repeat-string "^1.6.1"
 
+to-regex-range@^5.0.1:
+  version "5.0.1"
+  resolved "https://registry.yarnpkg.com/to-regex-range/-/to-regex-range-5.0.1.tgz#1648c44aae7c8d988a326018ed72f5b4dd0392e4"
+  integrity sha512-65P7iz6X5yEr1cwcgvQxbbIw7Uk3gOy5dIdtZ4rDveLqhrdJP+Li/Hx6tyK0NEb+2GCyneCMJiGqrADCSNk8sQ==
+  dependencies:
+    is-number "^7.0.0"
+
 to-regex@^3.0.1, to-regex@^3.0.2:
   version "3.0.2"
   resolved "https://registry.yarnpkg.com/to-regex/-/to-regex-3.0.2.tgz#13cfdd9b336552f30b51f33a8ae1b42a7a7599ce"
@@ -13321,6 +13360,17 @@ triple-beam@^1.2.0, triple-beam@^1.3.0:
   resolved "https://registry.yarnpkg.com/triple-beam/-/triple-beam-1.3.0.tgz#a595214c7298db8339eeeee083e4d10bd8cb8dd9"
   integrity sha512-XrHUvV5HpdLmIj4uVMxHggLbFSZYIn7HEWsqePZcI50pco+MPqJ50wMGY794X7AOOhxOBAjbkqfAbEe/QMp2Lw==
 
+ts-loader@^6.0.4:
+  version "6.0.4"
+  resolved "https://registry.yarnpkg.com/ts-loader/-/ts-loader-6.0.4.tgz#bc331ad91a887a60632d94c9f79448666f2c4b63"
+  integrity sha512-p2zJYe7OtwR+49kv4gs7v4dMrfYD1IPpOtqiSPCbe8oR+4zEBtdHwzM7A7M91F+suReqgzZrlClk4LRSSp882g==
+  dependencies:
+    chalk "^2.3.0"
+    enhanced-resolve "^4.0.0"
+    loader-utils "^1.0.2"
+    micromatch "^4.0.0"
+    semver "^6.0.0"
+
 ts-mocha@^6.0.0:
   version "6.0.0"
   resolved "https://registry.yarnpkg.com/ts-mocha/-/ts-mocha-6.0.0.tgz#40b8c5462ffce6f5dcee5ff729655b2958f26e50"