diff --git a/backend/transcode.py b/backend/transcode.py
index efb2e71..6ecf201 100644
--- a/backend/transcode.py
+++ b/backend/transcode.py
@@ -195,7 +195,10 @@ async def _run(cmd: List[str], on_status, out_dir: Path, entry_filename: str, so
     duration = await probe_duration(source) if source else 0.0
     await on_status("running", progress=0.0)
     # Machine-readable progress on stdout, separate from ffmpeg's normal stderr logging.
-    cmd = [cmd[0], "-progress", "pipe:1", "-nostats"] + cmd[1:]
+    # Insert right after the "ffmpeg" token, not cmd[0] — cmd is prefixed with `nice -n N`,
+    # and these flags belong to ffmpeg, not to nice.
+    ffmpeg_idx = cmd.index("ffmpeg")
+    cmd = cmd[:ffmpeg_idx + 1] + ["-progress", "pipe:1", "-nostats"] + cmd[ffmpeg_idx + 1:]
     try:
         proc = await asyncio.create_subprocess_exec(
             *cmd, stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE,