diff --git a/Lib/urllib.py b/Lib/urllib.py
index e32a771..3460a56 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1223,6 +1223,8 @@
     """
     # fastpath
     if not s:
+        if s is None:
+            raise TypeError('None object cannot be quoted')
         return s
 
     if encoding is not None or isinstance(s, unicode):