diff -r 01676a4c16ff Lib/os.py
--- a/Lib/os.py	Sun Dec 08 10:06:04 2013 +0100
+++ b/Lib/os.py	Sun Dec 08 13:07:51 2013 +0200
@@ -231,7 +231,7 @@
         head, tail = path.split(head)
     if head and tail and not path.exists(head):
         try:
-            makedirs(head, mode, exist_ok)
+            makedirs(head, exist_ok=exist_ok)
         except FileExistsError:
             # be happy if someone already created the path
             pass
diff -r 01676a4c16ff Lib/test/test_os.py
--- a/Lib/test/test_os.py	Sun Dec 08 10:06:04 2013 +0100
+++ b/Lib/test/test_os.py	Sun Dec 08 13:07:51 2013 +0200
@@ -894,6 +894,18 @@
                             'dir5', 'dir6')
         os.makedirs(path)
 
+    def test_mode(self):
+        with support.temp_umask(0o002):
+            base = support.TESTFN
+            parent = os.path.join(base, 'dir1')
+            path = os.path.join(parent, 'dir2')
+            os.makedirs(path, 0o555)
+            self.assertTrue(os.path.exists(path))
+            self.assertTrue(os.path.isdir(path))
+            if os.name != 'nt':
+                self.assertEqual(stat.S_IMODE(os.stat(path).st_mode), 0o555)
+            self.assertEqual(stat.S_IMODE(os.stat(parent).st_mode), 0o775)
+
     def test_exist_ok_existing_directory(self):
         path = os.path.join(support.TESTFN, 'dir1')
         mode = 0o777