diff --git a/yt_dlp/YoutubeDL.py b/yt_dlp/YoutubeDL.py
index b0f88ba86e..d2c83c346f 100644
--- a/yt_dlp/YoutubeDL.py
+++ b/yt_dlp/YoutubeDL.py
@@ -2149,7 +2149,7 @@ def selector_function(ctx):
                 mobj = re.match(
                     r'(?P<m>merge)?all(?P<t>video|audio)?(?P<l>lang)?', format_spec)
                 if mobj:
-                    mg, tp, la = mobj.groups()
+                    mg, tp, la = mobj.group('m', 't', 'l')
                     def selector_function(ctx):
                         formats = ctx['formats'][::-1]