diff -r ed4ffd602f4e Lib/ctypes/_endian.py
--- a/Lib/ctypes/_endian.py	Sun Aug 24 18:08:22 2014 -0500
+++ b/Lib/ctypes/_endian.py	Mon Aug 25 12:37:47 2014 +0300
@@ -45,6 +45,7 @@
 
     class BigEndianStructure(Structure, metaclass=_swapped_meta):
         """Structure with big endian byte order"""
+        __slots__ = ()
         _swappedbytes_ = None
 
 elif sys.byteorder == "big":
@@ -53,6 +54,7 @@
     BigEndianStructure = Structure
     class LittleEndianStructure(Structure, metaclass=_swapped_meta):
         """Structure with little endian byte order"""
+        __slots__ = ()
         _swappedbytes_ = None
 
 else:
diff -r ed4ffd602f4e Lib/ctypes/test/test_byteswap.py
--- a/Lib/ctypes/test/test_byteswap.py	Sun Aug 24 18:08:22 2014 -0500
+++ b/Lib/ctypes/test/test_byteswap.py	Mon Aug 25 12:37:47 2014 +0300
@@ -22,6 +22,26 @@
             setattr(bits, "i%s" % i, 1)
             dump(bits)
 
+    def test_slots(self):
+        class BigPoint(BigEndianStructure):
+            __slots__ = ()
+            _fields_ = [("x", c_int), ("y", c_int)]
+
+        class LowPoint(LittleEndianStructure):
+            __slots__ = ()
+            _fields_ = [("x", c_int), ("y", c_int)]
+
+        big = BigPoint()
+        little = LowPoint()
+        big.x = 4
+        big.y = 2
+        little.x = 2
+        little.y = 4
+        with self.assertRaises(AttributeError):
+            big.z = 42
+        with self.assertRaises(AttributeError):
+            little.z = 24
+
     def test_endian_short(self):
         if sys.byteorder == "little":
             self.assertIs(c_short.__ctype_le__, c_short)