diff --git a/preload.js b/preload.js
index 8c7e695..ddcb8aa 100644
--- a/preload.js
+++ b/preload.js
@@ -60,7 +60,7 @@ const Serial = {
     return board.fs_save(content || ' ', filename, dataConsumer)
   },
   uploadFile: async (src, dest, dataConsumer) => {
-    return board.fs_put(src, dest, dataConsumer)
+    return board.fs_put(src, dest.replaceAll(path.win32.sep, path.posix.sep), dataConsumer)
   },
   downloadFile: async (src, dest) => {
     let contents = await Serial.loadFile(src)
diff --git a/ui/arduino/store.js b/ui/arduino/store.js
index 3bcac48..2c93a7e 100644
--- a/ui/arduino/store.js
+++ b/ui/arduino/store.js
@@ -1536,7 +1536,7 @@ async function uploadFolder(srcPath, destPath, dataConsumer) {
         disk.getFullPath(srcPath, relativePath, ''),
         serial.getFullPath(destPath, relativePath, ''),
         (progress) => {
-          dataConsumer(progress, relativePath.slice(1))
+          dataConsumer(progress, relativePath)
         }
       )
     }