#9018: os.path.normcase() now raises a TypeError if the argument is not str or bytes.
diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 8d50294..7972aa9 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -78,6 +78,9 @@
"""Normalize case of pathname.
Makes all characters lowercase and all slashes into backslashes."""
+ if not isinstance(s, (bytes, str)):
+ raise TypeError("normcase() argument must be str or bytes, "
+ "not '{}'".format(s.__class__.__name__))
return s.replace(_get_altsep(s), _get_sep(s)).lower()