diff --git a/yt_dlp/postprocessor/sponsorblock.py b/yt_dlp/postprocessor/sponsorblock.py
index 7749ffe05..7f75561db 100644
--- a/yt_dlp/postprocessor/sponsorblock.py
+++ b/yt_dlp/postprocessor/sponsorblock.py
@@ -38,7 +38,7 @@ class SponsorBlockPP(FFmpegPostProcessor):
             return [], info
 
         self.to_screen('Fetching SponsorBlock segments')
-        info['sponsorblock_chapters'] = self._get_sponsor_chapters(info, info['duration'])
+        info['sponsorblock_chapters'] = self._get_sponsor_chapters(info, info.get('duration'))
         return [], info
 
     def _get_sponsor_chapters(self, info, duration):