diff -r 279c8c8e433d Lib/wsgiref/validate.py
--- a/Lib/wsgiref/validate.py	Thu Aug 01 00:08:16 2013 +0200
+++ b/Lib/wsgiref/validate.py	Wed Jul 31 16:44:48 2013 -0600
@@ -194,7 +194,7 @@
         self.input = wsgi_input
 
     def read(self, *args):
-        assert_(len(args) == 1)
+        assert_(len(args) <= 1)
         v = self.input.read(*args)
         assert_(type(v) is bytes)
         return v