diff --git a/package-lock.json b/package-lock.json
index b9d84bf55..365ac8b41 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -37,6 +37,7 @@
         "eslint-plugin-prettier": "^4.2.1",
         "eslint-plugin-promise": "^6.1.1",
         "prettier": "^2.8.3",
+        "type-fest": "^3.8.0",
         "typedoc": "^0.23.24",
         "typescript": "^4.9.4"
       },
@@ -3934,6 +3935,18 @@
         "url": "https://github.com/sponsors/sindresorhus"
       }
     },
+    "node_modules/serialize-error/node_modules/type-fest": {
+      "version": "0.13.1",
+      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.13.1.tgz",
+      "integrity": "sha512-34R7HTnG0XIJcBSn5XhDd7nNFPRcXYRZrBB2O2jdKqYODldSzBAqzsWoZYYvduky73toYS/ESqxPvkDf/F0XMg==",
+      "dev": true,
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/sindresorhus"
+      }
+    },
     "node_modules/shebang-command": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/shebang-command/-/shebang-command-2.0.0.tgz",
@@ -4245,12 +4258,12 @@
       }
     },
     "node_modules/type-fest": {
-      "version": "0.13.1",
-      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.13.1.tgz",
-      "integrity": "sha512-34R7HTnG0XIJcBSn5XhDd7nNFPRcXYRZrBB2O2jdKqYODldSzBAqzsWoZYYvduky73toYS/ESqxPvkDf/F0XMg==",
+      "version": "3.8.0",
+      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-3.8.0.tgz",
+      "integrity": "sha512-FVNSzGQz9Th+/9R6Lvv7WIAkstylfHN2/JYxkyhhmKFYh9At2DST8t6L6Lref9eYO8PXFTfG9Sg1Agg0K3vq3Q==",
       "dev": true,
       "engines": {
-        "node": ">=10"
+        "node": ">=14.16"
       },
       "funding": {
         "url": "https://github.com/sponsors/sindresorhus"
@@ -7376,6 +7389,14 @@
       "dev": true,
       "requires": {
         "type-fest": "^0.13.1"
+      },
+      "dependencies": {
+        "type-fest": {
+          "version": "0.13.1",
+          "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.13.1.tgz",
+          "integrity": "sha512-34R7HTnG0XIJcBSn5XhDd7nNFPRcXYRZrBB2O2jdKqYODldSzBAqzsWoZYYvduky73toYS/ESqxPvkDf/F0XMg==",
+          "dev": true
+        }
       }
     },
     "shebang-command": {
@@ -7610,9 +7631,9 @@
       }
     },
     "type-fest": {
-      "version": "0.13.1",
-      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.13.1.tgz",
-      "integrity": "sha512-34R7HTnG0XIJcBSn5XhDd7nNFPRcXYRZrBB2O2jdKqYODldSzBAqzsWoZYYvduky73toYS/ESqxPvkDf/F0XMg==",
+      "version": "3.8.0",
+      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-3.8.0.tgz",
+      "integrity": "sha512-FVNSzGQz9Th+/9R6Lvv7WIAkstylfHN2/JYxkyhhmKFYh9At2DST8t6L6Lref9eYO8PXFTfG9Sg1Agg0K3vq3Q==",
       "dev": true
     },
     "typed-array-length": {
diff --git a/package.json b/package.json
index 61918773f..9bddcdf83 100644
--- a/package.json
+++ b/package.json
@@ -101,6 +101,7 @@
     "eslint-plugin-prettier": "^4.2.1",
     "eslint-plugin-promise": "^6.1.1",
     "prettier": "^2.8.3",
+    "type-fest": "^3.8.0",
     "typedoc": "^0.23.24",
     "typescript": "^4.9.4"
   },
diff --git a/src/scenes/context.ts b/src/scenes/context.ts
index 703aa1022..2fc7f885a 100644
--- a/src/scenes/context.ts
+++ b/src/scenes/context.ts
@@ -3,52 +3,81 @@ import Composer from '../composer'
 import Context from '../context'
 import d from 'debug'
 import { SessionContext } from '../session'
+import type { HasAllOptionalProps } from './utilTypes'
 const debug = d('telegraf:scenes:context')
 
 const noop = () => Promise.resolve()
 const now = () => Math.floor(Date.now() / 1000)
 
-export interface SceneContext<D extends SceneSessionData = SceneSessionData>
-  extends Context {
-  session: SceneSession<D>
-  scene: SceneContextScene<SceneContext<D>, D>
-}
-
-export interface SceneSessionData {
+export type DefaultSceneSessionData = {
   current?: string
   expires?: number
   state?: object
 }
 
-export interface SceneSession<S extends SceneSessionData = SceneSessionData> {
+export type SceneSessionData<
+  S extends object,
+  MustBeValid extends boolean = false
+> = HasAllOptionalProps<S> extends never
+  ? MustBeValid extends true
+    ? never
+    : // This is needed to give the developer some info about what's wrong
+      'Error: All state properties must be optional.'
+  : {
+      current?: string
+      expires?: number
+      state?: S
+    }
+
+export interface SceneSession<
+  S extends SceneSessionData<object, true> = SceneSessionData<object>
+> {
   __scenes?: S
 }
 
-export interface SceneContextSceneOptions<D extends SceneSessionData> {
+export interface SceneContext<
+  D extends SceneSessionData<object, true> = SceneSessionData<object>
+> {
+  session: SceneSession<D>
+  scene: SceneContextScene<D>
+}
+
+export interface SceneContextSceneOptions<
+  D extends SceneSessionData<object, true>
+> {
   ttl?: number
   default?: string
   defaultSession: D
 }
 
+type RS<SD extends SceneSessionData<object, true>> = NonNullable<
+  NonNullable<SessionContext<SceneSession<SD>>['session']>['__scenes']
+>
+
+type D<SD extends SceneSessionData<object, true>> = NonNullable<RS<SD>['state']>
+
+type C<SD extends SceneSessionData<object, true>> = SessionContext<
+  SceneSession<SD>
+>
+
 export default class SceneContextScene<
-  C extends SessionContext<SceneSession<D>>,
-  D extends SceneSessionData = SceneSessionData
+  SD extends SceneSessionData<object, true>,
+  CC extends C<SD> = C<SD>
 > {
-  private readonly options: SceneContextSceneOptions<D>
+  private readonly options: SceneContextSceneOptions<SD>
 
   constructor(
-    private readonly ctx: C,
-    private readonly scenes: Map<string, BaseScene<C>>,
-    options: Partial<SceneContextSceneOptions<D>>
+    private readonly ctx: C<SD>,
+    private readonly scenes: Map<string, BaseScene<C<DefaultSceneSessionData>>>,
+    options: Partial<SceneContextSceneOptions<SD>>
   ) {
-    // @ts-expect-error {} might not be assignable to D
-    const fallbackSessionDefault: D = {}
+    const fallbackSessionDefault = {} as SD
 
     this.options = { defaultSession: fallbackSessionDefault, ...options }
   }
 
-  get session(): D {
-    const defaultSession = Object.assign({}, this.options.defaultSession)
+  get session(): RS<SD> {
+    const defaultSession = { ...this.options.defaultSession }
 
     let session = this.ctx.session?.__scenes ?? defaultSession
     if (session.expires !== undefined && session.expires < now()) {
@@ -62,11 +91,11 @@ export default class SceneContextScene<
     return session
   }
 
-  get state() {
+  get state(): D<SD> {
     return (this.session.state ??= {})
   }
 
-  set state(value) {
+  set state(value: D<SD>) {
     this.session.state = { ...value }
   }
 
@@ -82,7 +111,7 @@ export default class SceneContextScene<
       this.ctx.session.__scenes = Object.assign({}, this.options.defaultSession)
   }
 
-  async enter(sceneId: string, initialState: object = {}, silent = false) {
+  async enter(sceneId: string, initialState: D<SD> = {}, silent = false) {
     if (!this.scenes.has(sceneId)) {
       throw new Error(`Can't find scene: ${sceneId}`)
     }
diff --git a/src/scenes/stage.ts b/src/scenes/stage.ts
index 02003e1af..ebf33ac9c 100644
--- a/src/scenes/stage.ts
+++ b/src/scenes/stage.ts
@@ -1,18 +1,22 @@
 import { isSessionContext, SessionContext } from '../session'
 import SceneContextScene, {
+  DefaultSceneSessionData,
   SceneContextSceneOptions,
   SceneSession,
+  SceneContext,
   SceneSessionData,
 } from './context'
 import { BaseScene } from './base'
 import { Composer } from '../composer'
 import { Context } from '../context'
+import { Modify } from './utilTypes'
+
+type D = DefaultSceneSessionData
 
 export class Stage<
   C extends SessionContext<SceneSession<D>> & {
-    scene: SceneContextScene<C, D>
-  },
-  D extends SceneSessionData = SceneSessionData
+    scene: SceneContextScene<D>
+  }
 > extends Composer<C> {
   options: Partial<SceneContextSceneOptions<D>>
   scenes: Map<string, BaseScene<C>>
@@ -41,7 +45,7 @@ export class Stage<
     const handler = Composer.compose<C>([
       (ctx, next) => {
         const scenes: Map<string, BaseScene<C>> = this.scenes
-        const scene = new SceneContextScene<C, D>(ctx, scenes, this.options)
+        const scene = new SceneContextScene<object>(ctx, scenes, this.options)
         ctx.scene = scene
         return next()
       },
@@ -51,21 +55,21 @@ export class Stage<
     return Composer.optional(isSessionContext, handler)
   }
 
-  static enter<C extends Context & { scene: SceneContextScene<C> }>(
-    ...args: Parameters<SceneContextScene<C>['enter']>
+  static enter<D extends SceneSessionData<object, true>, C>(
+    ...args: Parameters<SceneContext<D>['scene']['enter']>
   ) {
-    return (ctx: C) => ctx.scene.enter(...args)
+    return (ctx: Modify<C, SceneContext<D>>) => ctx.scene.enter(...args)
   }
 
-  static reenter<C extends Context & { scene: SceneContextScene<C> }>(
-    ...args: Parameters<SceneContextScene<C>['reenter']>
+  static reenter<D extends SceneSessionData<object, true>, C>(
+    ...args: Parameters<SceneContext<D>['scene']['reenter']>
   ) {
-    return (ctx: C) => ctx.scene.reenter(...args)
+    return (ctx: Modify<C, SceneContext<D>>) => ctx.scene.reenter(...args)
   }
 
-  static leave<C extends Context & { scene: SceneContextScene<C> }>(
-    ...args: Parameters<SceneContextScene<C>['leave']>
+  static leave<D extends SceneSessionData<object, true>, C>(
+    ...args: Parameters<SceneContext<D>['scene']['leave']>
   ) {
-    return (ctx: C) => ctx.scene.leave(...args)
+    return (ctx: Modify<C, SceneContext<D>>) => ctx.scene.leave(...args)
   }
 }
diff --git a/src/scenes/utilTypes.ts b/src/scenes/utilTypes.ts
new file mode 100644
index 000000000..662bba294
--- /dev/null
+++ b/src/scenes/utilTypes.ts
@@ -0,0 +1,18 @@
+import type { HasRequiredKeys, IsEqual } from 'type-fest'
+
+// These are the magic utility types
+
+export type RequireAllOptionalProps<T extends object> =
+  HasRequiredKeys<T> extends true ? never : T
+
+// This ensures T extends RequireAllOptionalProps<T>
+// AND RequireAllOptionalProps<T> extend T
+// so in both directions
+export type HasAllOptionalProps<T extends object> = IsEqual<
+  T,
+  RequireAllOptionalProps<T>
+> extends true
+  ? T
+  : never
+
+export type Modify<T, K> = Omit<T, keyof K> & K
diff --git a/src/scenes/wizard/context.ts b/src/scenes/wizard/context.ts
index 8429f5c79..9af71a1b7 100644
--- a/src/scenes/wizard/context.ts
+++ b/src/scenes/wizard/context.ts
@@ -2,25 +2,35 @@ import SceneContextScene, { SceneSession, SceneSessionData } from '../context'
 import Context from '../../context'
 import { Middleware } from '../../middleware'
 import { SessionContext } from '../../session'
+import type { HasAllOptionalProps } from '../utilTypes'
 
-export interface WizardContext<D extends WizardSessionData = WizardSessionData>
-  extends Context {
-  session: WizardSession<D>
-  scene: SceneContextScene<WizardContext<D>, D>
-  wizard: WizardContextWizard<WizardContext<D>>
-}
+export type WizardSessionData<
+  T extends object = object,
+  MustBeValid extends boolean = false
+> = SceneSessionData<T> extends string
+  ? MustBeValid extends true
+    ? never
+    : SceneSessionData<T>
+  : SceneSessionData<T> & { cursor: number }
 
-export interface WizardSessionData extends SceneSessionData {
-  cursor: number
+// Adding `& Cursor` guarantees that we're not getting the string case
+export interface WizardContext<
+  D extends WizardSessionData<object, true> = WizardSessionData<object>
+> extends Context {
+  session: WizardSession<D>
+  scene: SceneContextScene<D>
+  wizard: WizardContextWizard<D>
 }
 
-export interface WizardSession<S extends WizardSessionData = WizardSessionData>
-  extends SceneSession<S> {}
+// Adding `& Cursor` guarantees that we're not getting the string case
+export interface WizardSession<
+  S extends WizardSessionData<object, true> = WizardSessionData<object>
+> extends SceneSession<S> {}
 
+// Adding `& Cursor` guarantees that we're not getting the string case
 export default class WizardContextWizard<
-  C extends SessionContext<WizardSession> & {
-    scene: SceneContextScene<C, WizardSessionData>
-  }
+  C extends WizardContext<D>,
+  D extends WizardSessionData<object, true> = WizardSessionData<object>
 > {
   readonly state: object
   constructor(
diff --git a/src/scenes/wizard/index.ts b/src/scenes/wizard/index.ts
index 1243d4955..b72b4d603 100644
--- a/src/scenes/wizard/index.ts
+++ b/src/scenes/wizard/index.ts
@@ -1,34 +1,37 @@
 import BaseScene, { SceneOptions } from '../base'
 import { Middleware, MiddlewareObj } from '../../middleware'
-import WizardContextWizard, { WizardSessionData } from './context'
+import WizardContextWizard, {
+  WizardSessionData,
+  WizardContext,
+} from './context'
 import Composer from '../../composer'
 import Context from '../../context'
 import SceneContextScene from '../context'
 
+type WC<T extends WizardSessionData<object, true> = WizardSessionData<object>> =
+  WizardContext<T>
+
 export class WizardScene<
-    C extends Context & {
-      scene: SceneContextScene<C, WizardSessionData>
-      wizard: WizardContextWizard<C>
-    }
+    T extends WizardSessionData<object, true> = WizardSessionData<object>
   >
-  extends BaseScene<C>
-  implements MiddlewareObj<C>
+  extends BaseScene<WC<T>>
+  implements MiddlewareObj<WC<T>>
 {
-  steps: Array<Middleware<C>>
+  steps: Array<Middleware<WC<T>>>
 
-  constructor(id: string, ...steps: Array<Middleware<C>>)
+  constructor(id: string, ...steps: Array<Middleware<WC<T>>>)
   constructor(
     id: string,
-    options: SceneOptions<C>,
-    ...steps: Array<Middleware<C>>
+    options: SceneOptions<WC<T>>,
+    ...steps: Array<Middleware<WC<T>>>
   )
   constructor(
     id: string,
-    options: SceneOptions<C> | Middleware<C>,
-    ...steps: Array<Middleware<C>>
+    options: SceneOptions<WC<T>> | Middleware<WC<T>>,
+    ...steps: Array<Middleware<WC<T>>>
   ) {
-    let opts: SceneOptions<C> | undefined
-    let s: Array<Middleware<C>>
+    let opts: SceneOptions<WC<T>> | undefined
+    let s: Array<Middleware<WC<T>>>
     if (typeof options === 'function' || 'middleware' in options) {
       opts = undefined
       s = [options, ...steps]
@@ -41,9 +44,9 @@ export class WizardScene<
   }
 
   middleware() {
-    return Composer.compose<C>([
+    return Composer.compose<WC<T>>([
       (ctx, next) => {
-        ctx.wizard = new WizardContextWizard<C>(ctx, this.steps)
+        ctx.wizard = new WizardContextWizard<WC<T>, T>(ctx, this.steps)
         return next()
       },
       super.middleware(),