diff --git a/redditbot.py b/redditbot.py
index 3ea0656..dd4554c 100644
--- a/redditbot.py
+++ b/redditbot.py
@@ -416,6 +416,19 @@ async def main():
                         if pmedia:
                             pmedia = urljoin(url, pmedia)
                             await _download_file(filename, pmedia)
+                            if await _get_file_mimetype(filename) == 'video/x-m4v':
+                                ofilename = filename + '.oc'
+                                os.rename(filename, ofilename)
+                                proc = await asyncio.create_subprocess_exec('ffmpeg', '-nostdin', '-y', '-i', ofilename, '-c', 'copy', '-f', 'mp4', filename)
+                                await proc.communicate()
+                                if not proc.returncode:
+                                    os.remove(ofilename)
+                                else:
+                                    os.rename(ofilename, filename)
+                                    try:
+                                        os.remove(filename)
+                                    except FileNotFoundError:
+                                        pass
                             files.append(filename)
                         if pdesc:
                             caplength = 1023 if pmedia else 4095