1 files changed, 4 insertions, 2 deletions
diff --git a/django/utils/datastructures.py b/django/utils/datastructures.py
index bc8fb07ef5..3d7c4275bb 100644
--- a/django/utils/datastructures.py
+++ b/django/utils/datastructures.py
@@ -42,7 +42,8 @@ class MergeDict:
 
 class SortedDict(dict):
     "A dictionary that keeps its keys in the order in which they're inserted."
-    def __init__(self, data={}):
+    def __init__(self, data=None):
+        if data is None: data = {}
         dict.__init__(self, data)
         self.keyOrder = data.keys()
 
@@ -123,8 +124,9 @@ class MultiValueDict(dict):
     def __copy__(self):
         return self.__class__(dict.items(self))
 
-    def __deepcopy__(self, memo={}):
+    def __deepcopy__(self, memo=None):
         import copy
+        if memo is None: memo = {}
         result = self.__class__()
         memo[id(self)] = result
         for key, value in dict.items(self):