diff --git a/youtube_dl/postprocessor/ffmpeg.py b/youtube_dl/postprocessor/ffmpeg.py
index 214825aa9..098af7aa4 100644
--- a/youtube_dl/postprocessor/ffmpeg.py
+++ b/youtube_dl/postprocessor/ffmpeg.py
@@ -607,6 +607,7 @@ class FFmpegSubtitlesConvertorPP(FFmpegPostProcessor):
             return [], info
         self._downloader.to_screen('[ffmpeg] Converting subtitles')
         sub_filenames = []
+        temp_srt_filenames = []
         for lang, sub in subs.items():
             ext = sub['ext']
             if ext == new_ext:
@@ -640,7 +641,7 @@ class FFmpegSubtitlesConvertorPP(FFmpegPostProcessor):
                 if new_ext == 'srt':
                     continue
                 else:
-                    sub_filenames.append(srt_file)
+                    temp_srt_filenames.append(srt_file)
 
             self.run_ffmpeg(old_file, new_file, ['-f', new_format])
 
@@ -650,4 +651,7 @@ class FFmpegSubtitlesConvertorPP(FFmpegPostProcessor):
                     'data': f.read(),
                 }
 
+        for f in temp_srt_filenames:
+            os.remove(encodeFilename(f))
+
         return sub_filenames, info