diff --git a/backend/src/activitypub/objects/image.ts b/backend/src/activitypub/objects/image.ts
index c6b3a21..0fb1df1 100644
--- a/backend/src/activitypub/objects/image.ts
+++ b/backend/src/activitypub/objects/image.ts
@@ -4,7 +4,9 @@ import type { Actor } from 'wildebeest/backend/src/activitypub/actors'
 export const IMAGE = 'Image'
 
 // https://www.w3.org/TR/activitystreams-vocabulary/#dfn-image
-export interface Image extends objects.Document {}
+export interface Image extends objects.Document {
+	description?: string
+}
 
 export async function createImage(domain: string, db: D1Database, actor: Actor, properties: any): Promise<Image> {
 	const actorId = new URL(actor.id)
diff --git a/backend/src/activitypub/objects/index.ts b/backend/src/activitypub/objects/index.ts
index a4f1c73..be4f40d 100644
--- a/backend/src/activitypub/objects/index.ts
+++ b/backend/src/activitypub/objects/index.ts
@@ -156,6 +156,16 @@ export async function updateObject(db: D1Database, properties: any, id: URL): Pr
 	return true
 }
 
+export async function updateObjectProperty(db: D1Database, obj: APObject, key: string, value: string) {
+	const { success, error } = await db
+		.prepare(`UPDATE objects SET properties=json_set(properties, '$.${key}', ?) WHERE id=?`)
+		.bind(value, obj.id.toString())
+		.run()
+	if (!success) {
+		throw new Error('SQL error: ' + error)
+	}
+}
+
 export async function getObjectById(db: D1Database, id: string | URL): Promise<APObject | null> {
 	return getObjectBy(db, 'id', id.toString())
 }
diff --git a/backend/src/errors/index.ts b/backend/src/errors/index.ts
index e62c26a..b402830 100644
--- a/backend/src/errors/index.ts
+++ b/backend/src/errors/index.ts
@@ -42,6 +42,10 @@ export function statusNotFound(id: string): Response {
 	return generateErrorResponse('Resource not found', 404, `Status "${id}" not found`)
 }
 
+export function mediaNotFound(id: string): Response {
+	return generateErrorResponse('Resource not found', 404, `Media "${id}" not found`)
+}
+
 export function exceededLimit(detail: string): Response {
 	return generateErrorResponse('Limit exceeded', 400, detail)
 }
diff --git a/backend/test/mastodon/media.spec.ts b/backend/test/mastodon/media.spec.ts
index c7a5f9e..e47ad8d 100644
--- a/backend/test/mastodon/media.spec.ts
+++ b/backend/test/mastodon/media.spec.ts
@@ -1,4 +1,6 @@
 import * as media from 'wildebeest/functions/api/v2/media'
+import { createImage } from 'wildebeest/backend/src/activitypub/objects/image'
+import * as media_id from 'wildebeest/functions/api/v2/media/[id]'
 import { createPerson } from 'wildebeest/backend/src/activitypub/actors'
 import { strict as assert } from 'node:assert/strict'
 import { makeDB, assertJSON, isUrlValid } from '../utils'
@@ -56,5 +58,32 @@ describe('Mastodon APIs', () => {
 			assert.equal(obj.type, 'Image')
 			assert.equal(obj[originalActorIdSymbol], connectedActor.id.toString())
 		})
+
+		test('update image description', async () => {
+			const db = await makeDB()
+			const connectedActor = await createPerson(domain, db, userKEK, 'sven@cloudflare.com')
+			const properties = {
+				url: 'https://cloudflare.com/image.jpg',
+				description: 'foo bar',
+			}
+			const image = await createImage(domain, db, connectedActor, properties)
+
+			const request = new Request('https://' + domain, {
+				method: 'PUT',
+				body: JSON.stringify({ description: 'new foo bar' }),
+				headers: {
+					'content-type': 'application/json',
+				},
+			})
+
+			const res = await media_id.handleRequestPut(db, image[mastodonIdSymbol]!, request)
+			assert.equal(res.status, 200)
+
+			const data = await res.json<any>()
+			assert.equal(data.description, 'new foo bar')
+
+			const newImage = (await objects.getObjectByMastodonId(db, image[mastodonIdSymbol]!)) as any
+			assert.equal(newImage.description, 'new foo bar')
+		})
 	})
 })
diff --git a/functions/api/v2/media/[id].ts b/functions/api/v2/media/[id].ts
new file mode 100644
index 0000000..eeef301
--- /dev/null
+++ b/functions/api/v2/media/[id].ts
@@ -0,0 +1,73 @@
+// https://docs.joinmastodon.org/methods/media/#update
+
+import { getObjectByMastodonId } from 'wildebeest/backend/src/activitypub/objects'
+import { mastodonIdSymbol } from 'wildebeest/backend/src/activitypub/objects'
+import { cors } from 'wildebeest/backend/src/utils/cors'
+import type { MediaAttachment } from 'wildebeest/backend/src/types/media'
+import type { Image } from 'wildebeest/backend/src/activitypub/objects/image'
+import { readBody } from 'wildebeest/backend/src/utils/body'
+import type { UUID } from 'wildebeest/backend/src/types'
+import type { Env } from 'wildebeest/backend/src/types/env'
+import type { ContextData } from 'wildebeest/backend/src/types/context'
+import * as errors from 'wildebeest/backend/src/errors'
+import { updateObjectProperty } from 'wildebeest/backend/src/activitypub/objects'
+
+export const onRequestPut: PagesFunction<Env, any, ContextData> = async ({ params, env, request }) => {
+	return handleRequestPut(env.DATABASE, params.id as UUID, request)
+}
+
+type UpdateMedia = {
+	description?: string
+}
+
+export async function handleRequestPut(db: D1Database, id: UUID, request: Request): Promise<Response> {
+	// Update the image properties
+	{
+		const image = (await getObjectByMastodonId(db, id)) as Image
+		if (image === null) {
+			return errors.mediaNotFound(id)
+		}
+
+		const body = await readBody<UpdateMedia>(request)
+
+		if (body.description !== undefined) {
+			await updateObjectProperty(db, image, 'description', body.description)
+		}
+	}
+
+	// reload the image for fresh state
+	const image = (await getObjectByMastodonId(db, id)) as Image
+
+	const res: MediaAttachment = {
+		id: image[mastodonIdSymbol]!,
+		url: image.url,
+		preview_url: image.url,
+		type: 'image',
+		meta: {
+			original: {
+				width: 640,
+				height: 480,
+				size: '640x480',
+				aspect: 1.3333333333333333,
+			},
+			small: {
+				width: 461,
+				height: 346,
+				size: '461x346',
+				aspect: 1.3323699421965318,
+			},
+			focus: {
+				x: -0.27,
+				y: 0.51,
+			},
+		},
+		description: image.description || '',
+		blurhash: 'UFBWY:8_0Jxv4mx]t8t64.%M-:IUWGWAt6M}',
+	}
+
+	const headers = {
+		...cors(),
+		'content-type': 'application/json; charset=utf-8',
+	}
+	return new Response(JSON.stringify(res), { headers })
+}