diff --git a/master/upload.go b/master/upload.go
index ee758094..79206035 100644
--- a/master/upload.go
+++ b/master/upload.go
@@ -134,14 +134,17 @@ func (s *UploadHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	dst, err := os.OpenFile(dstPath, os.O_CREATE|os.O_TRUNC, fs.FilePerm)
+	dst, err := os.OpenFile(dstPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, fs.FilePerm)
 	if err != nil {
 		log.Println("Upload file open operation failed:", err)
 		http.Error(w, fmt.Sprintf("Error writing uploaded file to disk: %s", err), http.StatusInternalServerError)
 		return
 	}
 	defer dst.Close()
-	io.Copy(dst, src)
+	if _, err := io.Copy(dst, src); err != nil {
+		log.Println("Error writing to destination:", err)
+		http.Error(w, fmt.Sprintf("Error writing zip file: %s", err), http.StatusInternalServerError)
+	}
 
 	switch typ {
 	case fs.KindEngine: