diff -r ac176a69d188 Lib/ipaddress.py
--- a/Lib/ipaddress.py	Sun Dec 28 22:14:23 2014 -0600
+++ b/Lib/ipaddress.py	Tue Dec 30 11:54:57 2014 +0200
@@ -387,6 +387,7 @@ class _TotalOrderingMixin:
     # __lt__ and __eq__
     # We avoid functools.total_ordering because it doesn't handle
     # NotImplemented correctly yet (http://bugs.python.org/issue10042)
+    __slots__ = ()
     def __eq__(self, other):
         raise NotImplementedError
     def __ne__(self, other):
@@ -419,6 +420,8 @@ class _IPAddressBase(_TotalOrderingMixin
 
     """The mother class."""
 
+    __slots__ = ()
+
     @property
     def exploded(self):
         """Return the longhand version of the IP address as a string."""
@@ -572,6 +575,8 @@ class _BaseAddress(_IPAddressBase):
     used by single IP addresses.
     """
 
+    __slots__ = ()
+
     def __init__(self, address):
         if (not isinstance(address, bytes)
             and '/' in str(address)):
@@ -1083,6 +1088,8 @@ class _BaseV4:
 
     """
 
+    __slots__ = ()
+    _version = 4
     # Equivalent to 255.255.255.255 or 32 bits of 1's.
     _ALL_ONES = (2**IPV4LENGTH) - 1
     _DECIMAL_DIGITS = frozenset('0123456789')
@@ -1095,9 +1102,6 @@ class _BaseV4:
     # when constructed (see _make_netmask()).
     _netmask_cache = {}
 
-    def __init__(self, address):
-        self._version = 4
-
     def _explode_shorthand_ip_string(self):
         return str(self)
 
@@ -1275,6 +1279,8 @@ class IPv4Address(_BaseV4, _BaseAddress)
 
     """Represent and manipulate single IPv4 Addresses."""
 
+    __slots__ = ('_ip', '__weakref__')
+
     def __init__(self, address):
 
         """
@@ -1292,7 +1298,6 @@ class IPv4Address(_BaseV4, _BaseAddress)
 
         """
         _BaseAddress.__init__(self, address)
-        _BaseV4.__init__(self, address)
 
         # Efficient constructor from integer.
         if isinstance(address, int):
@@ -1515,7 +1520,6 @@ class IPv4Network(_BaseV4, _BaseNetwork)
 
         """
 
-        _BaseV4.__init__(self, address)
         _BaseNetwork.__init__(self, address)
 
         # Constructing from a packed address or integer
@@ -1619,6 +1623,8 @@ class _BaseV6:
 
     """
 
+    __slots__ = ()
+    _version = 6
     _ALL_ONES = (2**IPV6LENGTH) - 1
     _HEXTET_COUNT = 8
     _HEX_DIGITS = frozenset('0123456789ABCDEFabcdef')
@@ -1628,9 +1634,6 @@ class _BaseV6:
     # when constructed (see _make_netmask()).
     _netmask_cache = {}
 
-    def __init__(self, address):
-        self._version = 6
-
     @classmethod
     def _make_netmask(cls, arg):
         """Make a (netmask, prefix_len) tuple from the given argument.
@@ -1899,6 +1902,8 @@ class IPv6Address(_BaseV6, _BaseAddress)
 
     """Represent and manipulate single IPv6 Addresses."""
 
+    __slots__ = ('_ip', '__weakref__')
+
     def __init__(self, address):
         """Instantiate a new IPv6 address object.
 
@@ -1917,7 +1922,6 @@ class IPv6Address(_BaseV6, _BaseAddress)
 
         """
         _BaseAddress.__init__(self, address)
-        _BaseV6.__init__(self, address)
 
         # Efficient constructor from integer.
         if isinstance(address, int):
@@ -2206,7 +2210,6 @@ class IPv6Network(_BaseV6, _BaseNetwork)
               supplied.
 
         """
-        _BaseV6.__init__(self, address)
         _BaseNetwork.__init__(self, address)
 
         # Efficient constructor from integer or packed address