diff --git a/yt_dlp/utils/_utils.py b/yt_dlp/utils/_utils.py
index 1de901b1b7..d9d0e9040c 100644
--- a/yt_dlp/utils/_utils.py
+++ b/yt_dlp/utils/_utils.py
@@ -167,7 +167,7 @@ def IDENTITY(x):
 
 NUMBER_RE = r'\d+(?:\.\d+)?'
 
-WINDOWS_RESERVED_NAMES_RE = fr'({'|'.join(
+WINDOWS_RESERVED_NAMES_RE = fr'({"|".join(
     ("CON", "CONOUT$", "CONIN$", "PRN", "AUX", "CLOCK$", "NUL")
     + tuple(f"{name:s}{num:d}" for name, num in itertools.product(("COM", "LPT"), range(0, 10)))
     + tuple(