diff --git a/thriftpy/_compat.py b/thriftpy/_compat.py
index 81eafcf..cb5a011 100644
--- a/thriftpy/_compat.py
+++ b/thriftpy/_compat.py
@@ -81,9 +81,8 @@ def __init__(self):
     varnames = ('self', ) + varnames
 
     def init(self):
-        kwargs = locals()
-        kwargs.pop('self')
-        self.__dict__.update(kwargs)
+        self.__dict__ = locals().copy()
+        del self.__dict__['self']
 
     code = init.__code__
     if PY3: