diff -r 5de1bd759f3b Lib/pathlib.py
--- a/Lib/pathlib.py	Sat Jan 23 14:15:48 2016 +0100
+++ b/Lib/pathlib.py	Sat Jan 23 17:14:53 2016 -0500
@@ -1065,6 +1065,8 @@
         """Iterate over this subtree and yield all existing files (of any
         kind, including directories) matching the given pattern.
         """
+        if not pattern:
+            raise ValueError("unacceptable pattern: {}".format(repr(pattern)))
         pattern = self._flavour.casefold(pattern)
         drv, root, pattern_parts = self._flavour.parse_parts((pattern,))
         if drv or root:
diff -r 5de1bd759f3b Lib/test/test_pathlib.py
--- a/Lib/test/test_pathlib.py	Sat Jan 23 14:15:48 2016 +0100
+++ b/Lib/test/test_pathlib.py	Sat Jan 23 17:14:53 2016 -0500
@@ -1969,6 +1969,11 @@
         else:
             self.assertRaises(NotImplementedError, pathlib.WindowsPath)
 
+    def test_glob(self):
+        p = self.cls()
+        gen = p.glob("")
+        self.assertRaises(ValueError, list, gen)
+
 
 @only_posix
 class PosixPathTest(_BasePathTest, unittest.TestCase):