diff --git a/web/static/src/ts/core/Widget.ts b/web/static/src/ts/core/Widget.ts
index 1cc986be..7aa71c99 100644
--- a/web/static/src/ts/core/Widget.ts
+++ b/web/static/src/ts/core/Widget.ts
@@ -23,8 +23,8 @@ interface Meta<T extends WEnv> {
   isStarted: boolean;
   isMounted: boolean;
   isDestroyed: boolean;
-  parent: Widget<T> | null;
-  children: { [key: number]: Widget<T> };
+  parent: Widget<T, {}> | null;
+  children: { [key: number]: Widget<T, {}> };
   // children mapping: from templateID to widgetID
   // should it be a map number => Widget?
   cmap: { [key: number]: number };
@@ -35,7 +35,7 @@ const patch = init([sdListeners, sdAttrs]);
 //------------------------------------------------------------------------------
 // Widget
 //------------------------------------------------------------------------------
-export class Widget<T extends WEnv> {
+export class Widget<T extends WEnv, Props> {
   __widget__: Meta<WEnv>;
   name: string = "widget";
   template: string = "<div></div>";
@@ -46,18 +46,18 @@ export class Widget<T extends WEnv> {
 
   env: T;
   state: Object = {};
-  props: any;
-  refs: { [key: string]: Widget<T> | HTMLElement | undefined } = {};
+  props: Props | undefined;
+  refs: { [key: string]: Widget<T, {}> | HTMLElement | undefined } = {};
 
   //--------------------------------------------------------------------------
   // Lifecycle
   //--------------------------------------------------------------------------
 
-  constructor(parent: Widget<T> | T, props?: any) {
+  constructor(parent: Widget<T, {}> | T, props?: Props) {
     wl.push(this);
     this.props = props;
     let id: number;
-    let p: Widget<T> | null = null;
+    let p: Widget<T, any> | null = null;
     if (parent instanceof Widget) {
       p = parent;
       this.env = parent.env;
@@ -83,7 +83,7 @@ export class Widget<T extends WEnv> {
 
   mounted() {}
 
-  shouldUpdate(nextProps: any): boolean {
+  shouldUpdate(nextProps: Props): boolean {
     return true;
   }
 
@@ -147,7 +147,7 @@ export class Widget<T extends WEnv> {
     }
   }
 
-  updateProps(nextProps?: any): Promise<void> {
+  updateProps(nextProps: Props): Promise<void> {
     const shouldUpdate = this.shouldUpdate(nextProps);
     this.props = nextProps;
     return shouldUpdate ? this.render() : Promise.resolve();
@@ -205,7 +205,7 @@ export class Widget<T extends WEnv> {
     }
   }
 
-  private visitSubTree(callback: (w: Widget<T>) => void) {
+  private visitSubTree(callback: (w: Widget<T, any>) => void) {
     callback(this);
     const children = this.__widget__.children;
     for (let id in children) {
diff --git a/web/static/src/ts/registry.ts b/web/static/src/ts/registry.ts
index 75e7ca71..8fa771e7 100644
--- a/web/static/src/ts/registry.ts
+++ b/web/static/src/ts/registry.ts
@@ -6,7 +6,7 @@ import { Type } from "./types";
 // Types
 //------------------------------------------------------------------------------
 
-type ActionWidget = Type<Widget<Env>>;
+type ActionWidget = Type<Widget<Env, {}>>;
 
 //------------------------------------------------------------------------------
 // Registry code
diff --git a/web/static/src/ts/services/action_manager.ts b/web/static/src/ts/services/action_manager.ts
index 5a099ed0..6fa5595f 100644
--- a/web/static/src/ts/services/action_manager.ts
+++ b/web/static/src/ts/services/action_manager.ts
@@ -33,7 +33,7 @@ export type Action = ClientAction | ActWindowAction;
 
 export interface ActionWidget {
   id: number;
-  Widget: Type<Widget<Env>>;
+  Widget: Type<Widget<Env, {}>>;
   props: any;
 }
 
diff --git a/web/static/src/ts/widgets/CRM.ts b/web/static/src/ts/widgets/CRM.ts
index a9299a74..0bdc27d0 100644
--- a/web/static/src/ts/widgets/CRM.ts
+++ b/web/static/src/ts/widgets/CRM.ts
@@ -7,7 +7,7 @@ const template = `
     </div>
 `;
 
-export class CRM extends Widget<Env> {
+export class CRM extends Widget<Env, {}> {
   name = "crm";
   template = template;
 }
diff --git a/web/static/src/ts/widgets/Counter.ts b/web/static/src/ts/widgets/Counter.ts
index c8c5de0b..e4e2cc9c 100644
--- a/web/static/src/ts/widgets/Counter.ts
+++ b/web/static/src/ts/widgets/Counter.ts
@@ -9,15 +9,19 @@ const template = `
     </div>
 `;
 
-export class Counter extends Widget<Env> {
+interface Props {
+  initialState?: number;
+}
+
+export class Counter extends Widget<Env, Props> {
   name = "counter";
   template = template;
   state = {
     counter: 0
   };
 
-  constructor(parent: Widget<Env>, props: { initialState?: number }) {
-    super(parent);
+  constructor(parent: Widget<Env, {}>, props: Props) {
+    super(parent, props);
     this.state.counter = props.initialState || 0;
   }
 
diff --git a/web/static/src/ts/widgets/Discuss.ts b/web/static/src/ts/widgets/Discuss.ts
index 9796f4cf..cd5fae28 100644
--- a/web/static/src/ts/widgets/Discuss.ts
+++ b/web/static/src/ts/widgets/Discuss.ts
@@ -23,7 +23,7 @@ const template = `
     </div>
 `;
 
-export class Discuss extends Widget<Env> {
+export class Discuss extends Widget<Env, {}> {
   name = "discuss";
   template = template;
   widgets = { Clock, Counter, ColorWidget };
@@ -54,7 +54,7 @@ export class Discuss extends Widget<Env> {
   }
 }
 
-class ColorWidget extends Widget<Env> {
+class ColorWidget extends Widget<Env, { color: "red" | "blue" }> {
   name = "colorwidget";
   template = `<div>Current Color: <t t-esc="props.color"/></div>`;
 }
diff --git a/web/static/src/ts/widgets/Navbar.ts b/web/static/src/ts/widgets/Navbar.ts
index 081f5b03..ba408d00 100644
--- a/web/static/src/ts/widgets/Navbar.ts
+++ b/web/static/src/ts/widgets/Navbar.ts
@@ -14,7 +14,7 @@ const template = `
     </div>
 `;
 
-export class Navbar extends Widget<Env> {
+export class Navbar extends Widget<Env, {}> {
   name = "navbar";
   template = template;
 
diff --git a/web/static/src/ts/widgets/clock.ts b/web/static/src/ts/widgets/clock.ts
index 0496777a..a0211a60 100644
--- a/web/static/src/ts/widgets/clock.ts
+++ b/web/static/src/ts/widgets/clock.ts
@@ -3,7 +3,7 @@ import { Env } from "../env";
 
 const template = `<div class="o_clock"><t t-esc="state.currentTime"/></div>`;
 
-export class Clock extends Widget<Env> {
+export class Clock extends Widget<Env, {}> {
   name = "clock";
   template = template;
   interval: any | undefined;
diff --git a/web/static/src/ts/widgets/root_widget.ts b/web/static/src/ts/widgets/root_widget.ts
index 714600a1..90d95b48 100644
--- a/web/static/src/ts/widgets/root_widget.ts
+++ b/web/static/src/ts/widgets/root_widget.ts
@@ -11,11 +11,11 @@ const template = `
     </div>
 `;
 
-export class RootWidget extends Widget<Env> {
+export class RootWidget extends Widget<Env, {}> {
   name = "root";
   template = template;
   widgets = { Navbar };
-  content: Widget<Env> | null = null;
+  content: Widget<Env, {}> | null = null;
 
   mounted() {
     this.env.actionManager.on("action_ready", this, this.setContentWidget);
diff --git a/web/static/tests/core/widget.test.ts b/web/static/tests/core/widget.test.ts
index 66708366..6d71908c 100644
--- a/web/static/tests/core/widget.test.ts
+++ b/web/static/tests/core/widget.test.ts
@@ -31,13 +31,13 @@ function nextTick(): Promise<void> {
   return Promise.resolve();
 }
 
-function children(w: Widget<WEnv>): Widget<WEnv>[] {
+function children(w: Widget<WEnv, {}>): Widget<WEnv, {}>[] {
   const childrenMap = w.__widget__.children;
   return Object.keys(childrenMap).map(id => childrenMap[id]);
 }
 
 // Test widgets
-class Counter extends Widget<WEnv> {
+class Counter extends Widget<WEnv, {}> {
   name = "counter";
   template = `<div><t t-esc="state.counter"/><button t-on-click="inc">Inc</button></div>`;
   state = {
@@ -49,13 +49,13 @@ class Counter extends Widget<WEnv> {
   }
 }
 
-class WidgetA extends Widget<WEnv> {
+class WidgetA extends Widget<WEnv, {}> {
   name = "a";
   template = `<div>Hello<t t-widget="b"/></div>`;
   widgets = { b: WidgetB };
 }
 
-class WidgetB extends Widget<WEnv> {
+class WidgetB extends Widget<WEnv, {}> {
   template = `<div>world</div>`;
 }
 
@@ -87,7 +87,7 @@ describe("basic widget properties", () => {
   });
 
   test("widget style and classname", async () => {
-    class StyledWidget extends Widget<WEnv> {
+    class StyledWidget extends Widget<WEnv, {}> {
       template = `<div style="font-weight:bold;" class="some-class">world</div>`;
     }
     const widget = new StyledWidget(env);
@@ -99,7 +99,7 @@ describe("basic widget properties", () => {
 
   test("updateState before first render does not trigger a render", async () => {
     let renderCalls = 0;
-    class TestW extends Widget<WEnv> {
+    class TestW extends Widget<WEnv, {}> {
       async willStart() {
         this.updateState({});
       }
@@ -132,7 +132,7 @@ describe("basic widget properties", () => {
 describe("lifecycle hooks", () => {
   test("willStart hook is called", async () => {
     let willstart = false;
-    class HookWidget extends Widget<WEnv> {
+    class HookWidget extends Widget<WEnv, {}> {
       async willStart() {
         willstart = true;
       }
@@ -144,7 +144,7 @@ describe("lifecycle hooks", () => {
 
   test("mounted hook is not called if not in DOM", async () => {
     let mounted = false;
-    class HookWidget extends Widget<WEnv> {
+    class HookWidget extends Widget<WEnv, {}> {
       async mounted() {
         mounted = true;
       }
@@ -157,7 +157,7 @@ describe("lifecycle hooks", () => {
 
   test("mounted hook is called if mounted in DOM", async () => {
     let mounted = false;
-    class HookWidget extends Widget<WEnv> {
+    class HookWidget extends Widget<WEnv, {}> {
       async mounted() {
         mounted = true;
       }
@@ -169,12 +169,12 @@ describe("lifecycle hooks", () => {
 
   test("willStart hook is called on subwidget", async () => {
     let ok = false;
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       name = "a";
       template = `<div><t t-widget="child"/></div>`;
       widgets = { child: ChildWidget };
     }
-    class ChildWidget extends Widget<WEnv> {
+    class ChildWidget extends Widget<WEnv, {}> {
       async willStart() {
         ok = true;
       }
@@ -188,7 +188,7 @@ describe("lifecycle hooks", () => {
     expect.assertions(4);
     let parentMounted = false;
     let childMounted = false;
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       name = "a";
       template = `<div><t t-widget="child"/></div>`;
       widgets = { child: ChildWidget };
@@ -197,7 +197,7 @@ describe("lifecycle hooks", () => {
         parentMounted = true;
       }
     }
-    class ChildWidget extends Widget<WEnv> {
+    class ChildWidget extends Widget<WEnv, {}> {
       mounted() {
         expect(document.body.contains(this.el)).toBe(true);
         expect(parentMounted).toBe(true);
@@ -212,7 +212,7 @@ describe("lifecycle hooks", () => {
   test("willStart, mounted on subwidget rendered after main is mounted in some other position", async () => {
     expect.assertions(3);
     let hookCounter = 0;
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       name = "a";
       state = { ok: false };
       template = `
@@ -228,7 +228,7 @@ describe("lifecycle hooks", () => {
       // patching algorithm
       widgets = { child: ChildWidget };
     }
-    class ChildWidget extends Widget<WEnv> {
+    class ChildWidget extends Widget<WEnv, {}> {
       async willStart() {
         hookCounter++;
       }
@@ -253,14 +253,14 @@ describe("lifecycle hooks", () => {
     expect.assertions(1);
     const target = document.createElement("div");
     document.body.appendChild(target);
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       name = "a";
       mounted() {
         const child = new ChildWidget(this);
         child.mount(this.el!);
       }
     }
-    class ChildWidget extends Widget<WEnv> {
+    class ChildWidget extends Widget<WEnv, {}> {
       mounted() {
         expect(this.el).toBeTruthy();
         done();
@@ -272,7 +272,7 @@ describe("lifecycle hooks", () => {
 
   test("widgets are unmounted and destroyed if no longer in DOM", async () => {
     let steps: string[] = [];
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       name = "a";
       state = { ok: true };
       template = `
@@ -282,7 +282,7 @@ describe("lifecycle hooks", () => {
       widgets = { child: ChildWidget };
     }
 
-    class ChildWidget extends Widget<WEnv> {
+    class ChildWidget extends Widget<WEnv, {}> {
       constructor(parent) {
         super(parent);
         steps.push("init");
@@ -315,7 +315,7 @@ describe("lifecycle hooks", () => {
 
   test("hooks are called in proper order in widget creation/destruction", async () => {
     let steps: string[] = [];
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       name = "a";
       template = `
           <div><t t-widget="child"/></div>`;
@@ -338,7 +338,7 @@ describe("lifecycle hooks", () => {
       }
     }
 
-    class ChildWidget extends Widget<WEnv> {
+    class ChildWidget extends Widget<WEnv, {}> {
       constructor(parent) {
         super(parent);
         steps.push("c init");
@@ -375,7 +375,7 @@ describe("lifecycle hooks", () => {
 
   test("shouldUpdate hook prevent rerendering", async () => {
     let shouldUpdate = false;
-    class TestWidget extends Widget<WEnv> {
+    class TestWidget extends Widget<WEnv, {}> {
       name = "a";
       template = `<div><t t-esc="props.val"/></div>`;
       shouldUpdate() {
@@ -406,7 +406,7 @@ describe("destroy method", () => {
 
   test("destroying a widget twice only call destroyed once", async () => {
     let count = 0;
-    class TestWidget extends Widget<WEnv> {
+    class TestWidget extends Widget<WEnv, {}> {
       destroyed() {
         count++;
       }
@@ -448,7 +448,7 @@ describe("destroy method", () => {
     let p: Promise<void> = new Promise(function(r) {
       resolve = r;
     });
-    class DelayedWidget extends Widget<WEnv> {
+    class DelayedWidget extends Widget<WEnv, {}> {
       willStart() {
         return p;
       }
@@ -488,7 +488,7 @@ describe("composition", () => {
   });
 
   test("t-refs on widget are widgets", async () => {
-    class WidgetC extends Widget<WEnv> {
+    class WidgetC extends Widget<WEnv, {}> {
       name = "a";
       template = `<div>Hello<t t-ref="mywidgetb" t-widget="b"/></div>`;
       widgets = { b: WidgetB };
@@ -499,7 +499,7 @@ describe("composition", () => {
   });
 
   test("modifying a sub widget", async () => {
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       template = `<div><t t-widget="Counter"/></div>`;
       widgets = { Counter };
     }
@@ -537,7 +537,7 @@ describe("composition", () => {
   });
 
   test("rerendering a widget with a sub widget", async () => {
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       template = `<div><t t-widget="Counter"/></div>`;
       widgets = { Counter };
     }
@@ -556,7 +556,7 @@ describe("composition", () => {
   });
 
   test("sub widgets are destroyed if no longer in dom, then recreated", async () => {
-    class ParentWidget extends Widget<WEnv> {
+    class ParentWidget extends Widget<WEnv, {}> {
       name = "a";
       state = { ok: true };
       template = `
@@ -582,14 +582,14 @@ describe("composition", () => {
 
 describe("props evaluation (with t-props directive)", () => {
   test("explicit object prop", async () => {
-    class Parent extends Widget<WEnv> {
+    class Parent extends Widget<WEnv, {}> {
       name = "a";
       template = `<div><t t-widget="child" t-props="{value: state.val}"/></div>`;
       widgets = { child: Child };
       state = { val: 42 };
     }
 
-    class Child extends Widget<WEnv> {
+    class Child extends Widget<WEnv, {}> {
       template = `<span><t t-esc="state.someval"/></span>`;
       state: { someval: number };
       constructor(parent: Parent, props: { value: number }) {
@@ -604,14 +604,14 @@ describe("props evaluation (with t-props directive)", () => {
   });
 
   test("object prop value", async () => {
-    class Parent extends Widget<WEnv> {
+    class Parent extends Widget<WEnv, {}> {
       name = "a";
       template = `<div><t t-widget="child" t-props="state"/></div>`;
       widgets = { child: Child };
       state = { val: 42 };
     }
 
-    class Child extends Widget<WEnv> {
+    class Child extends Widget<WEnv, {}> {
       template = `<span><t t-esc="state.someval"/></span>`;
       state: { someval: number };
       constructor(parent: Parent, props: { val: number }) {