diff --git a/src/delarte/hls.py b/src/delarte/hls.py
index 79e4c8d..c4f01b5 100644
--- a/src/delarte/hls.py
+++ b/src/delarte/hls.py
@@ -121,13 +121,17 @@ def fetch_program_sources(http_session, metadata, master_playlist_url):
         model.RenditionAudio(
             audio_media.language,
             audio_media.name.startswith("VO"),
-            audio_media.characteristics
-            and ("public.accessibility" in audio_media.characteristics),
+            (
+                audio_media.characteristics is not None
+                and ("public.accessibility" in audio_media.characteristics)
+            ),
         ),
         model.RenditionSubtitles(
             subtitles_media.language,
-            subtitles_media.characteristics
-            and ("public.accessibility" in subtitles_media.characteristics),
+            (
+                subtitles_media.characteristics is not None
+                and ("public.accessibility" in subtitles_media.characteristics)
+            ),
         )
         if subtitles_media
         else None,