diff --git a/lib/presentation/extensions/send_file_extension.dart b/lib/presentation/extensions/send_file_extension.dart
index 68be47220b..4042f80559 100644
--- a/lib/presentation/extensions/send_file_extension.dart
+++ b/lib/presentation/extensions/send_file_extension.dart
@@ -93,17 +93,15 @@ extension SendFileExtension on Room {
       }
 
       final formattedDateTime = DateTime.now().getFormattedCurrentDateTime();
-      final targetPath =
-          await File('${tempDir.path}/$formattedDateTime${fileInfo.fileName}')
-              .create();
-      fileInfo = fileInfo as ImageFileInfo;
+      final fileName = _generateThumbnailFileName(formattedDateTime, fileInfo);
+      final targetPath = await _createThumbnailFile(tempDir, fileName);
       await _generateThumbnail(
-        fileInfo,
+        fileInfo as ImageFileInfo,
         targetPath: targetPath.path,
         uploadStreamController: uploadStreamController,
       );
       thumbnail = ImageFileInfo(
-        fileInfo.fileName,
+        fileName,
         targetPath.path,
         await targetPath.length(),
         width: fileInfo.width,
@@ -430,6 +428,15 @@ extension SendFileExtension on Room {
     return eventId;
   }
 
+  Future<File> _createThumbnailFile(Directory tempDir, String fileName) async =>
+      await File('${tempDir.path}/$fileName').create();
+
+  String _generateThumbnailFileName(
+    String formattedDateTime,
+    FileInfo fileInfo,
+  ) =>
+      '$formattedDateTime${fileInfo.fileName}.${AppConfig.imageCompressFormmat.name}';
+
   Future<ImageFileInfo> convertHeicToJpgImage(ImageFileInfo fileInfo) async {
     final convertedFilePath =
         StorageDirectoryManager.instance.convertFileExtension(
@@ -632,7 +639,7 @@ extension SendFileExtension on Room {
       }
       uploadStreamController?.add(const Right(GenerateThumbnailSuccess()));
       return ImageFileInfo(
-        '${result.name}.${AppConfig.imageCompressFormmat.name}',
+        result.name,
         result.path,
         size,
         width: width,
diff --git a/lib/presentation/extensions/send_file_web_extension.dart b/lib/presentation/extensions/send_file_web_extension.dart
index a2a9a66afb..42f08ff02a 100644
--- a/lib/presentation/extensions/send_file_web_extension.dart
+++ b/lib/presentation/extensions/send_file_web_extension.dart
@@ -19,6 +19,7 @@ import 'package:fluffychat/utils/matrix_sdk_extensions/matrix_file_extension.dar
 import 'package:flutter_image_compress/flutter_image_compress.dart';
 import 'package:matrix/matrix.dart';
 import 'package:image/image.dart';
+import 'package:mime/mime.dart';
 import 'package:video_player/video_player.dart';
 import 'package:video_thumbnail/video_thumbnail.dart';
 
@@ -169,7 +170,7 @@ extension SendFileWebExtension on Room {
             : null;
         if (uploadThumbnail != null && uploadThumbnail.bytes != null) {
           final uploadThumbnailResponse = await mediaApi.uploadFileWeb(
-            file: file,
+            file: uploadThumbnail,
             cancelToken: cancelToken,
             onSendProgress: (receive, total) {
               uploadStreamController?.add(
@@ -442,11 +443,12 @@ extension SendFileWebExtension on Room {
         const Right(GenerateThumbnailSuccess()),
       );
 
+      final thumbnailFileName = _getVideoThumbnailFileName(originalFile);
+
       return MatrixImageFile(
         bytes: result,
-        name:
-            '${originalFile.name}.${AppConfig.videoThumbnailFormat.name.toLowerCase()}',
-        mimeType: originalFile.mimeType,
+        name: thumbnailFileName,
+        mimeType: lookupMimeType(thumbnailFileName) ?? 'image/jpeg',
         width: thumbnailBitmap?.width,
         height: thumbnailBitmap?.height,
         blurhash: blurHash,
@@ -464,6 +466,9 @@ extension SendFileWebExtension on Room {
     }
   }
 
+  String _getVideoThumbnailFileName(MatrixVideoFile originalFile) =>
+      '${originalFile.name}.${AppConfig.videoThumbnailFormat.name.toLowerCase()}';
+
   Future<int?> _getVideoDuration(
     MatrixVideoFile originalFile,
   ) async {