diff --git a/yt_dlp/utils.py b/yt_dlp/utils.py
index e9b889447..8c2c5593c 100644
--- a/yt_dlp/utils.py
+++ b/yt_dlp/utils.py
@@ -2057,6 +2057,9 @@ def get_windows_version():
 def write_string(s, out=None, encoding=None):
     assert isinstance(s, str)
     out = out or sys.stderr
+    # `sys.stderr` might be `None` (Ref: https://github.com/pyinstaller/pyinstaller/pull/7217)
+    if not out:
+        return
 
     if compat_os_name == 'nt' and supports_terminal_sequences(out):
         s = re.sub(r'([\r\n]+)', r' \1', s)