diff --git a/tsmark/video_annotator.py b/tsmark/video_annotator.py
index c89bd16..739ed1a 100755
--- a/tsmark/video_annotator.py
+++ b/tsmark/video_annotator.py
@@ -1315,8 +1315,7 @@ class World:
                     ffmpeg_args.append(
                         arg.format(
                             input=self.opts.video,
-                            output=f"{os.path.splitext(self.opts.video)[0]}.trim.{
-                                from_str}-{to_str}",
+                            output=f"{os.path.splitext(self.opts.video)[0]}.trim.{from_str}-{to_str}",
                             start_time=from_ft,
                             end_time=to_ft,
                         )