diff --git a/lib/src/client.dart b/lib/src/client.dart
index 0f2ce1c..2990bd3 100644
--- a/lib/src/client.dart
+++ b/lib/src/client.dart
@@ -489,7 +489,6 @@ class Client {
 
   /// Uploads a new user avatar for this user.
   Future<void> setAvatar(MatrixFile file) async {
-    await file.resize(width: Client.defaultThumbnailSize);
     final uploadResp = await upload(file);
     await jsonRequest(
         type: HTTPType.PUT,
diff --git a/lib/src/room.dart b/lib/src/room.dart
index 3be3291..d45cd15 100644
--- a/lib/src/room.dart
+++ b/lib/src/room.dart
@@ -478,13 +478,10 @@ class Room {
     Event inReplyTo,
     Map<String, dynamic> info,
     bool waitUntilSent = false,
-    int thumbnailMaxWidth = 800,
-    int thumbnailMaxHeight = 600,
-    int thumbnailQuality = 50,
+    MatrixFile thumbnail,
   }) async {
     Image fileImage;
     Image thumbnailImage;
-    MatrixFile thumbnail;
     EncryptedFile encryptedThumbnail;
     String thumbnailUploadResp;
 
@@ -505,17 +502,10 @@ class Room {
     }
 
     if (msgType == 'm.image') {
-      var thumbnailPathParts = file.path.split('/');
-      thumbnailPathParts.last = 'thumbnail_' + thumbnailPathParts.last + '.jpg';
-      final thumbnailPath = thumbnailPathParts.join('/');
-      thumbnail = MatrixFile(bytes: file.bytes, path: thumbnailPath);
-      await thumbnail.resize(
-        width: thumbnailMaxWidth,
-        height: thumbnailMaxHeight,
-        quality: thumbnailQuality,
-      );
       fileImage = decodeImage(file.bytes.toList());
-      thumbnailImage = decodeImage(thumbnail.bytes.toList());
+      if (thumbnail != null) {
+        thumbnailImage = decodeImage(thumbnail.bytes.toList());
+      }
     }
 
     final sendEncrypted = encrypted && client.fileEncryptionEnabled;
@@ -1257,7 +1247,6 @@ class Room {
   /// Uploads a new user avatar for this room. Returns the event ID of the new
   /// m.room.avatar event.
   Future<String> setAvatar(MatrixFile file) async {
-    await file.resize(width: Client.defaultThumbnailSize);
     final uploadResp = await client.upload(file);
     final setAvatarResp = await client.jsonRequest(
         type: HTTPType.PUT,
diff --git a/lib/src/utils/matrix_file.dart b/lib/src/utils/matrix_file.dart
index 82298f5..b16a838 100644
--- a/lib/src/utils/matrix_file.dart
+++ b/lib/src/utils/matrix_file.dart
@@ -1,43 +1,12 @@
 /// Workaround until [File] in dart:io and dart:html is unified
 
 import 'dart:typed_data';
-
-import 'package:image/image.dart';
 import 'package:matrix_file_e2ee/matrix_file_e2ee.dart';
 
 class MatrixFile {
   Uint8List bytes;
   String path;
 
-  /// If this file is an Image, this will resize it to the
-  /// given width and height. Otherwise returns false.
-  /// At least width or height must be set!
-  /// The bytes will be encoded as jpg.
-  Future<bool> resize({
-    int width,
-    int height,
-    int quality = 50,
-  }) async {
-    if (width == null && height == null) {
-      throw ('At least width or height must be set!');
-    }
-    Image image;
-    try {
-      image = decodeImage(bytes);
-    } catch (_) {
-      return false;
-    }
-    var resizedImage = image;
-    if (image.width > width) {
-      resizedImage = copyResize(image, width: width);
-    }
-    if (image.height > height) {
-      resizedImage = copyResize(image, height: height);
-    }
-    bytes = encodeJpg(resizedImage, quality: quality);
-    return true;
-  }
-
   /// Encrypts this file, changes the [bytes] and returns the
   /// encryption information as an [EncryptedFile].
   Future<EncryptedFile> encrypt() async {