diff --git a/yt_dlp/extractor/smotrim.py b/yt_dlp/extractor/smotrim.py
index 12a740e83..a0aee5bdd 100644
--- a/yt_dlp/extractor/smotrim.py
+++ b/yt_dlp/extractor/smotrim.py
@@ -59,6 +59,7 @@ class SmotrimIE(InfoExtractor):
                     ],
                 },
                 'is_live': True,
+                'duration': None,
             },
             'add_ie': ['RUTV'],
         },
@@ -75,6 +76,7 @@ class SmotrimIE(InfoExtractor):
                     ],
                 },
                 'is_live': True,
+                'duration': None,
             },
             'add_ie': ['RUTV'],
         },