# HG changeset patch
# Parent 032103c7ed47bbe9cc90281e023c32effef78d43

diff --git a/Lib/pathlib.py b/Lib/pathlib.py
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -755,11 +755,10 @@
     def with_suffix(self, suffix):
         """Return a new path with the file suffix changed (or added, if none)."""
         # XXX if suffix is None, should the current suffix be removed?
-        drv, root, parts = self._flavour.parse_parts((suffix,))
-        if drv or root or len(parts) != 1:
+        f = self._flavour
+        if f.sep in suffix or f.altsep and f.altsep in suffix:
             raise ValueError("Invalid suffix %r" % (suffix))
-        suffix = parts[0]
-        if not suffix.startswith('.'):
+        if (not suffix.startswith('.') or suffix == '.') and suffix != '':
             raise ValueError("Invalid suffix %r" % (suffix))
         name = self.name
         if not name: