diff --git a/src/core/apis/file.ts b/src/core/apis/file.ts
index 52a36557..3d457720 100644
--- a/src/core/apis/file.ts
+++ b/src/core/apis/file.ts
@@ -201,7 +201,7 @@ export class NTQQFileApi {
             elementType: ElementType.VIDEO,
             elementId: '',
             videoElement: {
-                fileName: fileName || _fileName,
+                fileName: (fileName || _fileName).replace(/\.[^/.]+$/, '.mp4'),
                 filePath: path,
                 videoMd5: md5,
                 thumbMd5,
diff --git a/src/onebot/action/go-cqhttp/DownloadFile.ts b/src/onebot/action/go-cqhttp/DownloadFile.ts
index cded4143..c95150d2 100644
--- a/src/onebot/action/go-cqhttp/DownloadFile.ts
+++ b/src/onebot/action/go-cqhttp/DownloadFile.ts
@@ -73,7 +73,7 @@ export default class GoCQHTTPDownloadFile extends BaseAction<Payload, FileRespon
                     headers[headerItem] = '';
                 } else {
                     const key = headerItem.substring(0, spilt);
-                    headers[key] = headerItem.substring(0, spilt + 1);
+                    headers[key] = headerItem.substring(spilt + 1);
                 }
             }
         }