diff --git a/src/main/index.ts b/src/main/index.ts
index 8f38c14..2ec580f 100644
--- a/src/main/index.ts
+++ b/src/main/index.ts
@@ -7,7 +7,7 @@ import { autoUpdater } from 'electron-updater'
 autoUpdater.autoDownload = false;
 autoUpdater.autoInstallOnAppQuit = true;
 
-let mainWindow;
+let mainWindow: BrowserWindow;
 let splashWindow: BrowserWindow;
 
 function createSplashWindow(): void {