diff --git a/packages/client/package.json b/packages/client/package.json
index b0d8fd56..14607205 100644
--- a/packages/client/package.json
+++ b/packages/client/package.json
@@ -13,6 +13,7 @@
     },
     "dependencies": {
         "@mtcute/tl": "^0.0.0",
-        "@mtcute/core": "^0.0.0"
+        "@mtcute/core": "^0.0.0",
+        "@mtcute/file-id": "^0.0.0"
     }
 }
diff --git a/packages/client/src/types/media/photo.ts b/packages/client/src/types/media/photo.ts
index 2cfe8766..4b6535b0 100644
--- a/packages/client/src/types/media/photo.ts
+++ b/packages/client/src/types/media/photo.ts
@@ -1,5 +1,5 @@
 import { tl } from '@mtcute/tl'
-import { FileLocation } from '../files/file-location'
+import { FileLocation } from '../files'
 import { TelegramClient } from '../../client'
 import { MtCuteArgumentError } from '../errors'
 import { Thumbnail } from './thumbnail'
@@ -119,8 +119,8 @@ export class Photo extends FileLocation {
                 _: 'inputPhoto',
                 id: this.raw.id,
                 accessHash: this.raw.accessHash,
-                fileReference: this.raw.fileReference
-            }
+                fileReference: this.raw.fileReference,
+            },
         }
     }
 
@@ -133,7 +133,7 @@ export class Photo extends FileLocation {
             // type is only really used for creating tl.InputMedia,
             // but since we are providing it directly, we can use `auto`
             type: 'auto',
-            file: this.inputMediaTl
+            file: this.inputMediaTl,
             // other fields are not needed since it's a forwarded media
         }
     }
diff --git a/packages/client/src/types/media/thumbnail.ts b/packages/client/src/types/media/thumbnail.ts
index be7c4da6..5ff66493 100644
--- a/packages/client/src/types/media/thumbnail.ts
+++ b/packages/client/src/types/media/thumbnail.ts
@@ -1,14 +1,15 @@
 import { TelegramClient } from '../../client'
-import { FileLocation } from '../files/file-location'
+import { FileLocation } from '../files'
 import { tl } from '@mtcute/tl'
 import {
     inflateSvgPath,
     strippedPhotoToJpg,
     svgPathToFile,
 } from '../../utils/file-utils'
-import { MtCuteTypeAssertionError } from '../errors'
+import { MtCuteArgumentError, MtCuteTypeAssertionError } from '../errors'
 import { assertTypeIs } from '../../utils/type-assertion'
 import { makeInspectable } from '../utils'
+import { tdFileId as td, toFileId, toUniqueFileId } from '@mtcute/file-id'
 
 /**
  * One size of some thumbnail
@@ -54,6 +55,7 @@ export class Thumbnail extends FileLocation {
     readonly height: number
 
     private _path?: string
+    private _media: tl.RawPhoto | tl.RawDocument
 
     constructor(
         client: TelegramClient,
@@ -102,6 +104,7 @@ export class Thumbnail extends FileLocation {
         this.raw = sz
         this.width = width
         this.height = height
+        this._media = media
 
         if (sz._ === 'photoPathSize') {
             this._path = inflateSvgPath(sz.bytes)
@@ -130,6 +133,59 @@ export class Thumbnail extends FileLocation {
 
         return this._path!
     }
+
+    private _fileId?: string
+    /**
+     * Get TDLib and Bot API compatible File ID
+     * representing this thumbnail.
+     */
+    get fileId(): string {
+        if (!this._fileId) {
+            if (this.raw._ !== 'photoSize' && this.raw._ !== 'photoSizeProgressive') {
+                throw new MtCuteArgumentError(`Cannot generate a file ID for "${this.raw.type}"`)
+            }
+
+            this._fileId = toFileId({
+                type: this._media._ === 'photo' ? td.FileType.Photo : td.FileType.Thumbnail,
+                dcId: this.dcId,
+                fileReference: this._media.fileReference,
+                location: {
+                    _: 'photo',
+                    id: this._media.id,
+                    accessHash: this._media.accessHash,
+                    volumeId: this.raw.location.volumeId,
+                    localId: this.raw.location.localId,
+                    source: {
+                        _: 'thumbnail',
+                        fileType: td.FileType.Photo,
+                        thumbnailType: this.raw.type,
+                    },
+                },
+            })
+        }
+
+        return this._fileId
+    }
+
+    private _uniqueFileId?: string
+    /**
+     * Get a unique File ID representing this thumbnail.
+     */
+    get uniqueFileId(): string {
+        if (!this._uniqueFileId) {
+            if (this.raw._ !== 'photoSize' && this.raw._ !== 'photoSizeProgressive') {
+                throw new MtCuteArgumentError(`Cannot generate a unique file ID for "${this.raw.type}"`)
+            }
+
+            this._uniqueFileId = toUniqueFileId(td.FileType.Photo, {
+                _: 'photo',
+                volumeId: this.raw.location.volumeId,
+                localId: this.raw.location.localId
+            })
+        }
+
+        return this._uniqueFileId
+    }
 }
 
 makeInspectable(Thumbnail, ['fileSize', 'dcId', 'width', 'height'], ['path'])