diff --git a/auto_convert_flv_to_mp4.py b/auto_convert_flv_to_mp4.py
index 848492f..fff77b9 100644
--- a/auto_convert_flv_to_mp4.py
+++ b/auto_convert_flv_to_mp4.py
@@ -4,8 +4,10 @@ import os
 
 for file in glob("*.flv"):
     new_file = file.replace(".flv", ".mp4")
+    if os.path.exists(new_file):
+        continue
     os.system(" ".join([
-        "ffmpeg", "-i", file,
+        "ffmpeg", "-y", "-i", file,
         "-c copy", "-f mp4",
         new_file,
     ]))