diff --git a/Cython/Compiler/ExprNodes.py b/Cython/Compiler/ExprNodes.py
index eab43780d45..4152555506a 100755
--- a/Cython/Compiler/ExprNodes.py
+++ b/Cython/Compiler/ExprNodes.py
@@ -3800,6 +3800,8 @@ def analyse_attribute(self, env, obj_type = None):
     def analyse_as_python_attribute(self, env, obj_type = None):
         if obj_type is None:
             obj_type = self.obj.type
+        # mangle private '__*' Python attributes used inside of a class
+        self.attribute = env.mangle_class_private_name(self.attribute)
         self.member = self.attribute
         self.type = py_object_type
         self.is_py_attr = 1
diff --git a/Cython/Compiler/Nodes.py b/Cython/Compiler/Nodes.py
index fcffcccc93b..ce7d5a73a68 100644
--- a/Cython/Compiler/Nodes.py
+++ b/Cython/Compiler/Nodes.py
@@ -1222,6 +1222,7 @@ def create_local_scope(self, env):
         if self.needs_closure:
             lenv = ClosureScope(name=self.entry.name,
                                 outer_scope = genv,
+                                parent_scope = env,
                                 scope_name=self.entry.cname)
         else:
             lenv = LocalScope(name=self.entry.name,
diff --git a/Cython/Compiler/Symtab.py b/Cython/Compiler/Symtab.py
index 80a7bd9ec9b..9714108419c 100644
--- a/Cython/Compiler/Symtab.py
+++ b/Cython/Compiler/Symtab.py
@@ -329,6 +329,11 @@ def mangle_internal(self, name):
         return self.mangle(prefix)
         #return self.parent_scope.mangle(prefix, self.name)
 
+    def mangle_class_private_name(self, name):
+        if self.parent_scope:
+            return self.parent_scope.mangle_class_private_name(name)
+        return name
+
     def next_id(self, name=None):
         # Return a cname fragment that is unique for this module
         counters = self.global_scope().id_counters
@@ -1535,8 +1540,8 @@ class ClosureScope(LocalScope):
 
     is_closure_scope = True
 
-    def __init__(self, name, scope_name, outer_scope):
-        LocalScope.__init__(self, name, outer_scope)
+    def __init__(self, name, scope_name, outer_scope, parent_scope=None):
+        LocalScope.__init__(self, name, outer_scope, parent_scope)
         self.closure_cname = "%s%s" % (Naming.closure_scope_prefix, scope_name)
 
 #    def mangle_closure_cnames(self, scope_var):
@@ -1626,9 +1631,22 @@ class PyClassScope(ClassScope):
 
     is_py_class_scope = 1
 
+    def mangle_class_private_name(self, name):
+        return self.mangle_special_name(name)
+
+    def mangle_special_name(self, name):
+        if name and name.startswith('__') and not name.endswith('__'):
+            name = EncodedString('_%s%s' % (self.class_name, name))
+        return name
+
+    def lookup_here(self, name):
+        name = self.mangle_special_name(name)
+        return ClassScope.lookup_here(self, name)
+
     def declare_var(self, name, type, pos,
                     cname = None, visibility = 'private',
                     api = 0, in_pxd = 0, is_cdef = 0):
+        name = self.mangle_special_name(name)
         if type is unspecified_type:
             type = py_object_type
         # Add an entry for a class attribute.
diff --git a/tests/bugs.txt b/tests/bugs.txt
index 2aa38548d28..e3d87cf10c1 100644
--- a/tests/bugs.txt
+++ b/tests/bugs.txt
@@ -1,7 +1,6 @@
 # This file contains tests corresponding to unresolved bugs,
 # which will be skipped in the normal testing run.
 
-methodmangling_T5
 class_attribute_init_values_T18
 numpy_ValueError_T172
 unsignedbehaviour_T184
diff --git a/tests/run/methodmangling_T5.py b/tests/run/methodmangling_T5.py
new file mode 100644
index 00000000000..7a1b7e2748e
--- /dev/null
+++ b/tests/run/methodmangling_T5.py
@@ -0,0 +1,78 @@
+# mode: run
+# ticket: 5
+
+class CyTest(object):
+    """
+    >>> cy = CyTest()
+    >>> '_CyTest__private' in dir(cy)
+    True
+    >>> cy._CyTest__private()
+    8
+    >>> '__private' in dir(cy)
+    False
+    >>> '_CyTest__x' in dir(cy)
+    True
+
+    >>> '__x' in dir(cy)
+    False
+    """
+    __x = 1
+    def __private(self): return 8
+
+    def get(self):
+        """
+        >>> CyTest().get()
+        (1, 1, 8)
+        """
+        return self._CyTest__x, self.__x, self.__private()
+
+    def get_inner(self):
+        """
+        >>> CyTest().get_inner()
+        (1, 1, 8)
+        """
+        def get(o):
+            return o._CyTest__x, o.__x, o.__private()
+        return get(self)
+
+class CyTestSub(CyTest):
+    """
+    >>> cy = CyTestSub()
+    >>> '_CyTestSub__private' in dir(cy)
+    True
+    >>> cy._CyTestSub__private()
+    9
+    >>> '_CyTest__private' in dir(cy)
+    True
+    >>> cy._CyTest__private()
+    8
+    >>> '__private' in dir(cy)
+    False
+
+    >>> '_CyTestSub__x' in dir(cy)
+    False
+    >>> '_CyTestSub__y' in dir(cy)
+    True
+    >>> '_CyTest__x' in dir(cy)
+    True
+    >>> '__x' in dir(cy)
+    False
+    """
+    __y = 2
+    def __private(self): return 9
+
+    def get(self):
+        """
+        >>> CyTestSub().get()
+        (1, 2, 2, 9)
+        """
+        return self._CyTest__x, self._CyTestSub__y, self.__y, self.__private()
+
+    def get_inner(self):
+        """
+        >>> CyTestSub().get_inner()
+        (1, 2, 2, 9)
+        """
+        def get(o):
+            return o._CyTest__x, o._CyTestSub__y, o.__y, o.__private()
+        return get(self)
diff --git a/tests/run/methodmangling_T5.pyx b/tests/run/methodmangling_T5.pyx
deleted file mode 100644
index 44b165b8354..00000000000
--- a/tests/run/methodmangling_T5.pyx
+++ /dev/null
@@ -1,22 +0,0 @@
-# ticket: 5
-# this is ticket #5
-
-__doc__ = u"""
->>> class PyTest(object):
-...     def __private(self): pass
-
->>> py = PyTest()
->>> '_PyTest__private' in dir(py)
-True
->>> '__private' in dir(py)
-False
-
->>> cy = CyTest()
->>> '_PyTest__private' in dir(cy)
-True
->>> '__private' in dir(cy)
-False
-"""
-
-class CyTest(object):
-    def __private(self): pass