diff --git a/youtube_dl/postprocessor/ffmpeg.py b/youtube_dl/postprocessor/ffmpeg.py
index 6f68f63f0..536870257 100644
--- a/youtube_dl/postprocessor/ffmpeg.py
+++ b/youtube_dl/postprocessor/ffmpeg.py
@@ -550,7 +550,7 @@ class FFmpegFixupStretchedPP(FFmpegPostProcessor):
         return [], info
 
     def _configuration_args(self, default=[]):
-        return [] # Make sure the users extra arguments don't mess up the fix
+        return []  # Make sure the users extra arguments don't mess up the fix
     
 
 class FFmpegFixupM4aPP(FFmpegPostProcessor):
@@ -571,7 +571,7 @@ class FFmpegFixupM4aPP(FFmpegPostProcessor):
         return [], info
 
     def _configuration_args(self, default=[]):
-        return [] # Make sure the users extra arguments don't mess up the fix
+        return []  # Make sure the users extra arguments don't mess up the fix
 
 class FFmpegFixupM3u8PP(FFmpegPostProcessor):
     def run(self, info):
@@ -588,7 +588,7 @@ class FFmpegFixupM3u8PP(FFmpegPostProcessor):
         return [], info
     
     def _configuration_args(self, default=[]):
-        return [] # Make sure the users extra arguments don't mess up the fix
+        return []  # Make sure the users extra arguments don't mess up the fix
 
 
 class FFmpegSubtitlesConvertorPP(FFmpegPostProcessor):